考研机试题 -- 排序、进位制、日期

成绩排序（稳定排序）

https://www.noobdream.com/DreamJudge/Issue/page/1151/

#include 
#include 
#include 
using namespace std;

const int N = 1010;

struct Stu {
	string name;
	int score;

	bool operator < (const Stu &w) const {
		return score < w.score;
	}
	bool operator > (const Stu &w) const {
		return score > w.score;
	}
} stu[N];

int main() {
	int n, m;
	cin >> n >> m;
		
	for(int i = 0; i < n; i ++) {
		cin >> stu[i].name >> stu[i].score;
	}
	if(m == 1)
		stable_sort(stu, stu + n);
	else
		stable_sort(stu, stu + n, greater<Stu>());
		
	for(int i = 0; i < n; i ++)
		cout << stu[i].name << " " << stu[i].score << endl;
	
	return 0;
} 

成绩排序2（双关键字排序）

https://www.noobdream.com/DreamJudge/Issue/page/1159/

#include 
#include 
using namespace std;

const int N = 110;

struct Stu {
	int id;
	int score;
	
	bool operator < (const Stu &w) const {
		if(score != w.score)
			return score < w.score;
		else 
			return id < w.id;
	}
} stu[N];

int main() {
	int n;
	cin >> n;
	
	for(int i = 0; i < n; i ++) {
		cin >> stu[i].id >> stu[i].score;
	}
	
	sort(stu, stu + n);
	
	for(int i = 0; i < n; i ++) {
		cout << stu[i].id << " " << stu[i].score << endl;
	}
	return 0;
}

数字排序（双关键字排序）

https://blog.csdn.net/horizon_7887/article/details/128911379

#include 
#include 
using namespace std;

const int N = 1010;

int n;
struct node {
	int a;
	int sum; //sum是各位和 
	//从大到小排序，重载大于号 
	bool operator > (const node &w) const {
		if(sum == w.sum)
			return a < w.a;
		return sum > w.sum;
	} 	
} p[N];

//计算各位和 
int add_sum(int a) {
	int sum = 0;
	while(a) {
		sum += a % 10;
		a /= 10;
	}
	return sum;
}

int main() {
	cin >> n;
	for(int i = 0; i < n; i ++) {
		cin >> p[i].a;
		p[i].sum = add_sum(p[i].a);
	}
		
	sort(p, p + n, greater<node>()); //从大到小排序加参数 greater()
	
	for(int i = 0; i < n; i ++) {
		cout << p[i].a << " " << p[i].sum << endl;
	}
	return 0;
} 

进制转换（进位制，高精度除法）

https://www.noobdream.com/DreamJudge/Issue/page/1178/

#include 
#include 
#include 
#include 
using namespace std;

vector<int> div(vector<int> &A, int b, int r) {
	vector<int> C;
	for(int i = A.size() - 1; i >= 0; i --) {
		r = r * 10 + A[i];
		C.push_back(r / b);
		r = r % b;	
	}
	reverse(C.begin(), C.end());
	while(C.size() > 1 && C.back() == 0) 
		C.pop_back();
	return C;
}

int main() {
	string c;
	while(cin >> c) {
		vector<int> A;
		
		for(int i = c.size() - 1; i >= 0; i --) {
			A.push_back(c[i] - '0');	
		}
		string res;
		while(true) {
			res = res + to_string(A[0] % 2);
			A = div(A, 2, 0);
			if(A.size() == 1 && A[0] == 0)
				break; 
		}
		
		for(int i = res.size() - 1; i >= 0; i --)
			cout << res[i];
			
		cout << endl;
	}
	
	return 0;
}

打印日期

https://www.noobdream.com/DreamJudge/Issue/page/1410/

#include 
using namespace std;

int months[13] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

int is_leap(int year) {
	if(year % 100 != 0 && year % 4 == 0 || year % 400 == 0)
		return 1;
	return 0;	
}

int main() {
	int y, s;
	while(cin >> y >> s) {
		int d = 0, m = 1;
		if(is_leap(y))
			months[2] = 29;
		else
			months[2] = 28;
			
		while(s --) {
			d ++;
			if(d > months[m]) {
				d = 1;
				m ++;
				if(m > 12) {
					m = 1;
					y ++;
				}
			}
			
		}		
		printf("%04d-%02d-%02d\n", y, m, d);
	}	
	
	return 0;
} 

日期累加

https://www.noobdream.com/DreamJudge/Issue/page/1446/
枚举a会超时，枚举m不会

#include 
#include 
#include 
#include 
using namespace std;


const int N = 1010;
int month[13] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

int is_leap(int year) {
	if(year % 4 == 0 && year % 100 != 0 || year % 400 == 0)
		return 1;
	return 0;
}

int main() {
	int T, y, m, d, a;
	cin >> T;
	while(T --) {
		cin >> y >> m >> d >> a;
		is_leap(y) == 1 ? month[2] = 29 : month[2] = 28;	
		d += a;
		//枚举月份
		while(d > month[m]) {
			d -= month[m];
			m ++;

			if(m > 12) {
				y ++;
				m = 1;	
				is_leap(y) == 1 ? month[2] = 29 : month[2] = 28;	
			}
		} 		
		printf("%4d-%02d-%02d\n", y, m, d);
	}
	
	return 0;
}