PAT 基础编程题目集（编程题1-38）题解

PAT

基础编程题目集（编程题1-38）题解

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7-1 — 7-38（已更新至最新！）

链接：https://pan.baidu.com/s/1LL4c5Uv2Kyj6H53q9xECjA
提取码：i4x5
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基础编程题目集（编程题1-38）
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序

这里是基础编程题目集（编程题1-38）
该部分考察较为基础，基本算法主要包括模拟、数论、二分、排序等，深入一些的算法有约瑟夫环、DFS、高精等
本章可能涉及到的模板有：
003 高精度模板
006 分数类模板
具体模板详见数据结构专题系列
接下来就是题解部分了，每道算法题都标注有对应的算法标签，对于那些易错、较难或是测试点比较特殊的题目会着重标注，本章推荐的题目有：

7-16 求符合给定条件的整数集 (15 分)	枚举
7-18 二分法求多项式单根 (20 分)	二分答案
7-28 猴子选大王 (20 分)	约瑟夫环
7-33 有理数加法 (15 分)	数论 + 分数
7-37 整数分解为若干项之和 (20 分)	DFS
7-38 数列求和-加强版 (20分)	数论 + 高精

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7-1 厘米换算英尺英寸 (15 分)

算法标签: 模拟

#include
using namespace std;

int main(){
	int n;
	cin >> n;
	double f = n*1.0;
	int x1 = int(f/30.48);
	int x2 = int((f-x1*30.48)/(30.48/12.00));
	cout << x1 << " " << x2 << endl;
	
	return 0;
} 

7-2 然后是几点 (15 分)

算法标签: 模拟

#include
using namespace std;

int main(){
	int time,n;
	cin >> time >> n;
	if(n<0){
		n = n % 1440;
		n = (n+1440) % 1440;
	}
	int h = time / 100;
	int m = time % 100;
	int m1 = n % 60;
	m += m1;
	if(m>=60){
		h++;
		m -= 60;
	}
	int h1 = n/60;
	h += h1;
	if(h>=24){
		h -= 24;
	}
	if(m<10){
		cout << h << "0" << m << endl;
	}else{
		cout << h << m << endl;
	}
	
	
	return 0;
}

7-3 逆序的三位数 (10 分)

算法标签: 数论

#include
using namespace std;

int main(){
	int n1;
	cin >> n1;
	int n2 = 0;
	while(n1){
		n2*=10;
		n2 += n1%10;
		n1/=10;
	}
	cout << n2 << endl;
	return 0;
}

7-4 BCD解密 (10 分)

算法标签: 进制

#include
using namespace std;

int main(){
	int n;
	cin >> n;
	if(n<=9){
		cout << n << endl;
	}else{
		cout << n/16 << n%16 << endl;
	}
	
	return 0;
}

7-5 表格输出 (5 分)

算法标签: 字符串

#include
using namespace std;

int main(){
	cout << "------------------------------------" << endl;
	cout << "Province      Area(km2)   Pop.(10K)" << endl;
	cout << "------------------------------------" << endl;
	cout << "Anhui         139600.00   6461.00" << endl;
	cout << "Beijing        16410.54   1180.70" << endl;
	cout << "Chongqing      82400.00   3144.23" << endl;
	cout << "Shanghai        6340.50   1360.26" << endl;
	cout << "Zhejiang      101800.00   4894.00" << endl;
	cout << "------------------------------------" << endl;
	
	return 0;
}

7-6 混合类型数据格式化输入 (5 分)

算法标签: 输入/输出

#include
using namespace std;

int main(){
	double f1,f2;
	int d;
	char c;
	scanf("%lf %d %c %lf",&f1,&d,&c,&f2);
	printf("%c %d %.2lf %.2lf\n",c,d,f1,f2);
	return 0;
}

7-7 12-24小时制 (15 分)

算法标签: 模拟

#include
using namespace std;

int main(){
	int h,m;
	scanf("%d:%d",&h,&m);
	if(h==12){
		printf("%d:%d PM\n",h,m);	
	}else if(h>12){
		h-=12;
		printf("%d:%d PM\n",h,m);
	}else{
		printf("%d:%d AM\n",h,m);
	}
	
	return 0;
}

7-8 超速判断 (10 分)

算法标签: 模拟

#include
using namespace std;

int main(){
	int n;
	cin >> n;
	if(n>60){
		printf("Speed: %d - Speeding\n",n);
	}else{
		printf("Speed: %d - OK\n",n);
	}
	
	return 0;
}

7-9 用天平找小球 (10 分)

算法标签: 排序

#include
using namespace std;

int main(){
	int a,b,c;
	cin >> a >> b >> c;
	if(a==b){
		cout << "C";
	}else if(b==c){
		cout << "A";
	}else{
		cout << "B";
	}
	
	return 0;
}

7-10 计算工资 (15 分)

算法标签: 分支

#include
using namespace std;

int main(){
	int y,h;
	int cnt;
	cin >> y >> h;
	if(y>=5){
		cnt = 50;
	}else{
		cnt = 30;
	}
	int ans = 0;
	if(h<=40){
		ans += cnt*h;
	}else{
		ans	+= cnt*40;
		ans += (h-40)*cnt*1.5;
	}
	printf("%d.00\n",ans);
	return 0;
}

7-11 分段计算居民水费 (10 分)

算法标签: 分支

#include
using namespace std;

int main(){
	double x;
	cin >> x;
	double y;
	if(x<=15){
		y = 4.0*x/3.0;
	}else{
		y = 2.5*x-17.5;
	}
	printf("%.2lf\n",y);
	return 0;
}

7-12 两个数的简单计算器 (10 分)

算法标签: 模拟

#include
using namespace std;

int main(){
	int x,y;
	char op;
	scanf("%d %c %d",&x,&op,&y);
	if(op=='+'){
		cout << x+y << endl;
	}else if(op=='-'){
		cout << x-y << endl;
	}else if(op=='*'){
		cout << x*y << endl; 
	}else if(op=='/'){
		cout << x/y << endl; 
	}else if(op=='%'){
		cout << x%y << endl; 
	}else{
		cout << "ERROR" << endl; 
	}
	
	return 0;
}

7-13 日K蜡烛图 (15 分)

算法标签: 模拟

#include
using namespace std;

int main(){
	double Open,High,Low,Close;
	cin >> Open >> High >> Low >> Close;
	string s = "";
	bool f1=0,f2=0;
	if(Open<Close){
		s+="R-Hollow";
	}else if(fabs(Open-Close)<1e-3){
		s+="R-Cross";
	}else{
		s+="BW-Solid";
	}
	if(High>Close && fabs(High-Close)>1e-3 && High>Open && fabs(High-Open)>1e-3){
		f1 = 1;
	}
	
	if(Low<Close && fabs(Low-Close)>1e-3 && Low<Open && fabs(Low-Open)>1e-3){
		f2 = 1;
	}
	
	if(f1 && f2){
		s += " with Lower Shadow and Upper Shadow";
	}else if(f1){
		s += " with Upper Shadow";
	}else if(f2){
		s += " with Lower Shadow";
	}
	cout << s << endl;
	return 0;
}

7-14 求整数段和 (15 分)

算法标签: 模拟

#include
using namespace std;

int main(){
	int a,b;
	cin >> a >> b;
	int cnt = 0;
	int sum = 0;
	for(int i=a;i<=b;i++){
		cnt++;
		printf("%5d",i);
		if(cnt%5==0){
			cout << endl;
		}
		sum+=i;
	}
	if(cnt%5!=0){
		cout << endl;
	}
	printf("Sum = %d\n",sum);
	return 0;
}

7-15 计算圆周率 (15 分)

算法标签: 分数

#include
using namespace std;

double fact(int t){
	double s = 1.0;
	for(int i=1;i<=t;i++){
		s*=i;
	}
	return s;
}
double fact2(int t){
	double s = 1.0;
	for(int i=1;i<=t;i+=2){
		s*=i;
	}
	return s;
}
int main(){
	double f;
	cin >> f;
	double sum1 = 0.0;
	double sum2 = 1.0;
	int fenzi = 1;
	int fenmu = 3;
	while(fabs(sum2-sum1)>=f){
		sum1 = sum2;
		double s1 = fact(fenzi);
		fenzi++;
		double s2 = fact2(fenmu);
		fenmu+=2;
		sum2 += s1/s2;
	}
	sum2*=2;
	printf("%.6lf\n",sum2);
	return 0;
}

7-16 求符合给定条件的整数集 (15 分)

算法标签: 数论 + 模拟

#include
using namespace std;
bool vis[15];

int main(){
	int a;
	cin >> a;
	int cnt = 0;
	int bit = 0;
	for(int i=a;i<=a+3;i++){
		if(!vis[i] && bit<3){
			vis[i] = 1;
			bit++;
			for(int j=a;j<=a+3;j++){
				if(!vis[j] && bit<3){
					vis[j] = 1;
					bit++;
					for(int k=a;k<=a+3;k++){
						if(!vis[k] && bit<3){
							vis[k] = 1;
							bit++;
							cnt++;
							if(cnt%6!=1){
								cout << " " << i << j << k;
							}else{
								cout << i << j << k;
							}
							if(cnt%6==0){
								cout << endl;
							}
							bit--;
							vis[k] = 0;
						}
					}
					vis[j] = 0;
					bit--;
				}
			}
			vis[i] = 0;
			bit--;
		}
	}
	
	return 0;
}

7-17 爬动的蠕虫 (15 分)

算法标签: 模拟

#include
using namespace std;

int main(){
	int N,U,D;
	cin >> N >> U >> D;
	int cnt = 0;
	int sum = 0;
	while(sum<N){
		if(cnt%2==0){
			sum += U;
		}else{
			sum -= D;
		}
		cnt++;
	}
	cout << cnt << endl;
	
	return 0;
}

7-18 二分法求多项式单根 (20 分)

算法标签: 二分

#include
using namespace std;

double a3,a2,a1,a0;
double cal(double x){
	return a3*x*x*x + a2*x*x + a1*x + a0;	
}

int main(){
	cin >> a3 >> a2 >> a1 >> a0;
	double left,right;
	cin >> left >> right;
	double ans;
	if(fabs(cal(left))<1e-5 || fabs(cal(right))<1e-5){
		if(cal(left)==0){
			ans = left;
		}else{
			ans = right;
		}
	}else{
		while(left<=right && fabs(right-left)>1e-5){
			double mid = (left+right)/2.0; 
			if(fabs(cal(mid))<1e-5){
				ans = mid;
				break;
			}
			if(cal(left)*cal(mid)<0){
				right = mid;
			}else if(cal(mid)*cal(right)){
				left = mid;
			}
		}	
	}
	
	printf("%.2lf\n",ans);
	
	return 0;
}

7-19 支票面额 (15 分)

算法标签: 数论 + 模拟

#include
using namespace std;

int main(){
	int n;
	cin >> n;
	int y=-1,f=-1;
	for(int i=0;i<=99;i++){
		for(int j=i+1;j<=99;j++){
			if(199*i+n == 98*j){
				y = i;
				f = j;
				break;
			}
		}
	}
	if(y==-1){
		cout << "No Solution" << endl; 
	}else{
		cout << y << "." << f << endl;
	}
	return 0;
}

7-20 打印九九口诀表 (15 分)

算法标签: 输入/输出

#include
using namespace std;

int main(){
	int N;
	cin >> N;
	for(int i=1;i<=N;i++){
		for(int j=1;j<=i;j++){
			printf("%d*%d=%-4d",j,i,i*j);
		}
		printf("\n");
	}
	
	return 0;
}

7-21 求特殊方程的正整数解 (15 分)

算法标签: 数论 + 模拟

#include
using namespace std;

int main(){
	int N;
	cin >> N;
	int cnt = 0;
	for(int x=1;x<=sqrt(N);x++){
		for(int y=x;y<=sqrt(N);y++){
			if(x*x+y*y==N){
				printf("%d %d\n",x,y);
				cnt++;
			}
		}
	}
	if(!cnt){
		printf("No Solution\n");
	}
	return 0;
}

7-22 龟兔赛跑 (20 分)

算法标签: 模拟

#include
using namespace std;

int main(){
	int t;
	cin >> t;
	int rabbit = 0;
	int turtle = 0;
	int f = 0;
	while(t){
		if(t>=10){
			if(f){
				turtle += 3*10;
				f--;
			}else{
				rabbit += 9*10;
				turtle += 3*10;
				if(rabbit>turtle){
					f = 3;
				}
			}
			t -= 10;
		}else{
			if(f--){
				turtle += 3*t;
			}else{
				rabbit += 9*t;
				turtle += 3*t;
			}
			t = 0;
		}
	}
	
	if(rabbit>turtle){
		cout << "^_^" << " " << rabbit;
	}else if(rabbit==turtle){
		cout << "-_-" << " " << rabbit;
	}else{
		cout << "@_@" << " " << turtle;
	}
	return 0;
}

7-23 币值转换 (20 分)

算法标签: 模拟

#include
using namespace std;
int a[15];
int main(){
	int n;
	cin >> n;
	if(n==0){
		cout << "a" ;
		return 0;
	}
	int cnt = 0;
	while(n){
		a[cnt++] = n%10;
		n/=10;
	}
	int down;
	for(int i=0;i<cnt;i++){
		if(a[i]==0){
			continue; 
		}else{
			down = i;
			break;
		}
	}
	bool f = 0;
	for(int i=cnt-1;i>=down;i--){
		if(a[i]==0 && f){
			
		}else if(a[i] == 0 && !f){
			f = 1;
		}else{
			if(f){
				cout << (char)(0 +'a');
			}
			f = 0;
			cout << (char)(a[i]+'a');
		}
		if(i==8){
			cout << "Y";
			f = 0;
		}else if(i==4){
			cout << "W";
			f = 0;
		}else if(i%4==3 && !f){
			cout << "Q";
		}else if(i%4==2 && !f){
			cout << "B";
		}else if(i%4==1 && !f){
			cout << "S";
		}
	}
	return 0;
}

7-24 约分最简分式 (15 分)

算法标签: 数论，分数

#include
using namespace std;
int gcd(int a,int b){
	if(b==0){
		return a;
	}else{
		return gcd(b,a%b);
	}
} 
int main(){
	int up,down;
	scanf("%d/%d",&up,&down);
	int g = gcd(up,down);
	up/=g;
	down/=g;
	printf("%d/%d\n",up,down);
	return 0;
}

7-25 念数字 (15 分)

算法标签: 字符串 + 模拟

#include
using namespace std;
char s[15][10] = {"ling","yi","er","san","si","wu","liu","qi","ba","jiu"};
int a[15];
int cnt = 0;
int main(){
	int n;
	cin >> n;
	if(n<0){
		cout << "fu ";
	}else if(n==0){
		cout << "ling" << endl;
		return 0;
	}
	n = abs(n);
	while(n){
		a[cnt++] = n%10;
		n/=10;
	}
	for(int i=cnt-1;i>=0;i--){
		if(i==0){
			printf("%s",s[a[i]]);
		}else{
			printf("%s ",s[a[i]]);
		}
	}
	return 0;
}

7-26 单词长度 (15 分)

算法标签: 字符串

#include
using namespace std;

int main(){
	string s;
	getline(cin,s);
	int cnt = 0;
	int count = 0;
	for(int i=0;i<s.size();i++){
		if((s[i]==' ' || s[i]=='.')&& cnt){
			if(count == 0){
				printf("%d",cnt);
			}else{
				printf(" %d",cnt);
			}
			count++;
			cnt = 0;
		}else if(s[i]==' ' && !cnt){
			
		}else{
			cnt++;
		}
	}
	return 0;
}

7-27 冒泡法排序 (20 分)

算法标签: 排序 + 模拟

#include
using namespace std;
int a[105];
int main(){
	int N,K;
	cin >> N >> K;
	for(int i=0;i<N;i++){
		cin >> a[i];
	} 
	for(int i=0;i<K;i++){
		for(int j=0;j<N-i-1;j++){
			if(a[j]>a[j+1]){
				swap(a[j],a[j+1]);
			}
		}
	}
	for(int i=0;i<N;i++){
		if(i==0){
			printf("%d",a[i]);
		}else{
			printf(" %d",a[i]);
		}
	}
	return 0;
} 

7-28 猴子选大王 (20 分)

算法标签: 约瑟夫环

#include
using namespace std;
int dp[1005];
int main(){
	dp[1] = 0;
	int N;
	cin >> N;
	for(int i=2;i<=N;i++){
		dp[i] = (dp[i-1]+3)%i;
	}
	cout << dp[N]+1 << endl;
	return 0;
} 

7-29 删除字符串中的子串 (20 分)

算法标签: 字符串 + 模拟

#include
using namespace std;

int main(){
	string s1,s2;
	getline(cin,s1);
	getline(cin,s2);
	int len = s2.size();
	int f = s1.find(s2);
	while(f!=-1){
		s1 = s1.substr(0,f) + s1.substr(f+len);
		f = s1.find(s2);
	}
	cout << s1 << endl;
	return 0;
} 

7-30 字符串的冒泡排序 (20 分)

算法标签: 排序 + 模拟

#include
using namespace std;
char a[105][15];
char temp[15];
int main(){
	int N,K;
	cin >> N >> K;
	for(int i=0;i<N;i++){
		scanf("%s",a[i]);
	} 
	for(int i=0;i<K;i++){
		for(int j=0;j<N-i-1;j++){
			if(strcmp(a[j],a[j+1])>0){
				strcpy(temp,a[j]);
				strcpy(a[j],a[j+1]);
				strcpy(a[j+1],temp);
			}
		}
	}
	for(int i=0;i<N;i++){
		printf("%s\n",a[i]);
	} 
	return 0;
} 

7-31 字符串循环左移 (20 分)

算法标签: 模拟

#include
using namespace std;
char s[105];
char ans[105];
int main(){
	char ch;
	int cnt = 0;
	while(scanf("%c",&ch) && ch!='\n'){
		s[cnt++] = ch;
	}
	s[cnt] = '\n';
	int N;
	cin >> N;
	int len = strlen(s)-1;
	N %= len;
	for(int i=0;i<N;i++){
		ans[len-N+i] = s[i];
	}
	for(int i=N;i<len;i++){
		ans[i-N] = s[i];
	}
	ans[len+1] = '\0';
	printf("%s\n",ans); 
	return 0;
} 

7-32 说反话-加强版 (20 分)

算法标签: 字符串 + 模拟

#include
using namespace std;
string s[250005];

int main(){
	int j = 0;
	while((cin >> s[j])){
		j++; 
	}
	for(int i=j-1;i>=0;i--){
		if(i!=0){
			cout << s[i] << " ";	
		}else{
			cout << s[i] <<endl;
		}
	}	
	return 0;
}

7-33 有理数加法 (15 分)

算法标签: 数论，分数

#include
using namespace std;

struct Fraction{
	int up;
	int down;
};

int gcd(int a,int b){
	if(b==0){
		return a;
	}else{
		return gcd(b,a%b);
	} 
}

Fraction reduction(Fraction f){
	if(f.up == 0){
		f.down = 1;
	}
	
	if(f.down < 0 ){
		f.up = -f.up;
		f.down = -f.down;
	}
	
	int g = gcd(max(f.up,f.down),min(f.up,f.down));
	f.up /= g;
	f.down /=g;
	
	return f;
}

Fraction add(Fraction f1,Fraction f2){
	Fraction ans;
	int g = gcd(max(f1.down,f2.down),min(f1.down,f2.down));
	ans.down = f1.down*f2.down/g;
	ans.up = f1.down*f2.up/g + f1.up*f2.down/g;
	ans = reduction(ans);
	return ans;
}

int main(){
	Fraction f1,f2;
	scanf("%d/%d",&f1.up,&f1.down);
	scanf("%d/%d",&f2.up,&f2.down);
	Fraction ans;
	ans = add(f1,f2);
	if(ans.down == 1){
		printf("%d\n",ans.up);
	}else{
		printf("%d/%d",ans.up,ans.down);
	}
	return 0;
} 

7-34 通讯录的录入与显示 (10 分)

算法标签: 模拟

#include
using namespace std;
struct info{
	string name;
	string birth;
	string sex;
	string telephone;
	string phone;
};
info in[15];
int main(){
	int N;
	cin >> N;
	for(int i=0;i<N;i++){
		cin >> in[i].name >> in[i].birth >> in[i].sex >> in[i].telephone >> in[i].phone;
	}
	int K;
	cin >> K;
	for(int i=0;i<K;i++){
		int t;
		cin >> t;
		if(t>=0 && t<N){
			cout << in[t].name << " " << in[t].telephone << " " << in[t].phone << " " <<
			in[t].sex << " " << in[t].birth << endl;
		}else{
			cout << "Not Found" << endl;
		}	
	}
	return 0;
} 

7-35 有理数均值 (20 分)

算法标签: 数论，分数

#include
using namespace std;
struct Fraction{
	int up;
	int down;
};

int gcd(int a,int b){
	if(b==0){
		return a;
	}else{
		return gcd(b,a%b);
	} 
}

Fraction reduction(Fraction f){
	if(f.up == 0){
		f.down = 1;
	}
	
	if(f.down < 0 ){
		f.up = -f.up;
		f.down = -f.down;
	}
	
	int g = gcd(max(f.up,f.down),min(f.up,f.down));
	f.up /= g;
	f.down /=g;
	
	return f;
}

Fraction add(Fraction f1,Fraction f2){
	Fraction ans;
	int g = gcd(max(f1.down,f2.down),min(f1.down,f2.down));
	ans.down = f1.down*f2.down/g;
	ans.up = f1.down*f2.up/g + f1.up*f2.down/g;
	ans = reduction(ans);
	return ans;
}

int main(){
	Fraction ans;
	ans.down = 1;
	ans.up = 0;
	int N;
	cin >> N;
	for(int i=0;i<N;i++){
		Fraction num;
		scanf("%d/%d",&num.up,&num.down);
		ans = add(ans,num);
	}
	ans.down *= N;
	ans = reduction(ans);
	if(ans.down==1){
		printf("%d\n",ans.up);
	}else{
		printf("%d/%d\n",ans.up,ans.down);
	}
	return 0;
} 

7-36 复数四则运算 (15 分)

算法标签: 数论，复数

#include
using namespace std;

int main(){
	double a1,a2,b1,b2;
	scanf("%lf%lf%lf%lf",&a1,&a2,&b1,&b2);
	double res1,res2;
	res1 = a1 + b1;
	res2 = a2 + b2;
	printf("(%.1lf%+.1lfi) + (%.1lf%+.1lfi) = ",a1,a2,b1,b2);
	
	if(fabs(res1)<1e-1 && fabs(res2)<1e-1){
		printf("0.0\n");
	}else if(fabs(res1)<1e-1){
		printf("%.1lfi\n",res2);
	}else if(fabs(res2)<1e-1){
		printf("%.1lf\n",res1);
	}else{
		printf("%.1lf%+.1lfi\n",res1,res2);
	}
	
	res1 = a1 - b1;
	res2 = a2 - b2;
	printf("(%.1lf%+.1lfi) - (%.1lf%+.1lfi) = ",a1,a2,b1,b2);
	if(fabs(res1)<1e-1 && fabs(res2)<1e-1){
		printf("0.0\n");
	}else if(fabs(res1)<1e-1){
		printf("%.1lfi\n",res2);
	}else if(fabs(res2)<1e-1){
		printf("%.1lf\n",res1);
	}else{
		printf("%.1lf%+.1lfi\n",res1,res2);
	}
	
	res1 = a1 * b1 - a2 * b2;
	res2 = a1 * b2 + a2 * b1;
	printf("(%.1lf%+.1lfi) * (%.1lf%+.1lfi) = ",a1,a2,b1,b2);
	if(fabs(res1)<1e-1 && fabs(res2)<1e-1){
		printf("0.0\n");
	}else if(fabs(res1)<1e-1){
		printf("%.1lfi\n",res2);
	}else if(fabs(res2)<1e-1){
		printf("%.1lf\n",res1);
	}else{
		printf("%.1lf%+.1lfi\n",res1,res2);
	}
	
	res1 = (a1 * b1 + a2 * b2)/(b1 * b1 + b2 * b2);
	res2 = (a2 * b1 - a1 * b2)/(b1 * b1 + b2 * b2);
	printf("(%.1lf%+.1lfi) / (%.1lf%+.1lfi) = ",a1,a2,b1,b2);
	if(fabs(res1)<1e-1 && fabs(res2)<1e-1){
		printf("0.0\n");
	}else if(fabs(res1)<1e-1){
		printf("%.1lfi\n",res2);
	}else if(fabs(res2)<1e-1){
		printf("%.1lf\n",res1);
	}else{
		printf("%.1lf%+.1lfi\n",res1,res2);
	}
	
	return 0;
} 

7-37 整数分解为若干项之和 (20 分)

算法标签: DFS

#include
using namespace std;
int a[35];
int cnt = 0;
int N;
void dfs(int depth,int num,int index){
	if(num==0){
		printf("%d=",N);
		for(int i=0;i<depth;i++){
			if(i==0){
				printf("%d",a[i]);
			}else{
				printf("+%d",a[i]);
			}
		}
		cnt++;
		if(cnt%4==0){
			printf("\n");
		}else{
			if(a[0]!=N){
				printf(";");	
			}
		}
	}	
	for(int i=index;i<=num;i++){
		a[depth] = i;
		dfs(depth+1,num-i,i);
	}
}

int main(){
	cin >> N;
	dfs(0,N,1);
	
	return 0;
} 

7-38 数列求和-加强版 (20 分)

算法标签: 高精加

#include
using namespace std;
const int maxn = 2e5+5;
int a[maxn];
int main(){
	int A,N;
	cin >> A >> N;
	for(int i=0;i<N;i++){
		a[i] = (N-i)*A;
	} 
	if(N==0){
		printf("0\n");
		return 0;
	}
	int jw = 0;
	for(int i=0;i<N;i++){
		a[i] = (a[i] + jw);
		jw = a[i]/10;
		a[i] %=10;
	}
	
	int cnt = 0;
	while(jw){
		a[N+cnt] = jw%10;
		jw/=10;
		cnt++;
	}
	
	for(int i=N+cnt-1;i>=0;i--){
		printf("%d",a[i]);
	}
	printf("\n");
	return 0;
}