HDOJ1754 I Hate It 【线段树】

I Hate It

Time Limit: 9000/3000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)

Total Submission(s): 35417    Accepted Submission(s): 13958

Problem Description

很多学校流行一种比较的习惯。老师们很喜欢询问，从某某到某某当中，分数最高的是多少。
这让很多学生很反感。

不管你喜不喜欢，现在需要你做的是，就是按照老师的要求，写一个程序，模拟老师的询问。当然，老师有时候需要更新某位同学的成绩。

 

Input

本题目包含多组测试，请处理到文件结束。
在每个测试的第一行，有两个正整数 N 和 M ( 0<N<=200000,0<M<5000 )，分别代表学生的数目和操作的数目。
学生ID编号分别从1编到N。
第二行包含N个整数，代表这N个学生的初始成绩，其中第i个数代表ID为i的学生的成绩。
接下来有M行。每一行有一个字符 C (只取'Q'或'U') ，和两个正整数A，B。
当C为'Q'的时候，表示这是一条询问操作，它询问ID从A到B(包括A,B)的学生当中，成绩最高的是多少。
当C为'U'的时候，表示这是一条更新操作，要求把ID为A的学生的成绩更改为B。

 

Output

对于每一次询问操作，在一行里面输出最高成绩。

 

Sample Input

   
   
   
   

    
    
    
    5 6
1 2 3 4 5
Q 1 5
U 3 6
Q 3 4
Q 4 5
U 2 9
Q 1 5
   
   
   
   

 

Sample Output

   
   
   
   

    
    
    
    5
6
5
9


    
    
    
    
 
     
 
      Hint 
     
Huge input,the C function scanf() will work better than cin 
    
   
   
   
   

这题验证了宏定义要比自定义函数慢。但不知道为啥，然后问了下老师，答复是“函数调用参数是计算好的，只计算一次；宏定义没有计算，运行时每次都要计算。”

Run ID	Submit Time	Judge Status	Pro.ID	Exe.Time	Exe.Memory	Code Len.	Language	Author
10955721	2014-07-07 11:20:55	Accepted	1754	1109MS	7156K	1513 B	G++	长木
10955685	2014-07-07 11:18:05	Time Limit Exceeded	1754	3000MS	7144K	1491 B	G++	长木

最新代码：

#include <stdio.h>
#include <string.h>
#define maxn 200002
#define lson l, mid, rt << 1
#define rson mid + 1, r, rt << 1 | 1

int tree[maxn << 2];

int max(int a, int b){
	return a > b ? a : b;
}

void pushUp(int rt){
	tree[rt] = max(tree[rt << 1], tree[rt << 1 | 1]);
}

void build(int l, int r, int rt)
{
	if(l == r){
		scanf("%d", &tree[rt]);
		return;
	}
	int mid = (l + r) >> 1;
	build(lson);
	build(rson);
	pushUp(rt);
}

void update(int pos, int val, int l, int r, int rt)
{
	if(l == r){
		tree[rt] = val; return;
	}
	int mid = (l + r) >> 1;
	if(pos <= mid) update(pos, val, lson);
	else update(pos, val, rson);
	pushUp(rt);
}

int query(int left, int right, int l, int r, int rt)
{
	if(left == l && right == r) return tree[rt];
	int mid = (l + r) >> 1;
	if(right <= mid) return query(left, right, lson);
	else if(left > mid) return query(left, right, rson);
	else return max(query(left, mid, lson), query(mid + 1, right, rson));
}

int main()
{
	int n, m, a, b;
	char com[2];
	while(scanf("%d%d", &n, &m) != EOF){
		build(1, n, 1);
		while(m--){
			scanf("%s%d%d", com, &a, &b);
			if(com[0] == 'Q') 
				printf("%d\n", query(a, b, 1, n, 1));
			else update(a, b, 1, n, 1);
		}
	}
	return 0;
}

AC：

#include <stdio.h>
#define maxn 200002

struct Node{
	int left, right;
	int max;
} tree[maxn << 2];
int stu[maxn];

int MAX(int a, int b)
{
	return a > b ? a : b;
}

void build(int left, int right, int rt)
{
	tree[rt].left = left; tree[rt].right = right;
	if(left == right){
		tree[rt].max = stu[left]; return;
	}
	
	int mid = (left + right) >> 1;
	build(left, mid, rt << 1);
	build(mid + 1, right, rt << 1 | 1);
	
	tree[rt].max = MAX(tree[rt<<1].max, tree[rt<<1|1].max);
}

void update(int pos, int val, int rt)
{
	if(tree[rt].left == tree[rt].right){
		tree[rt].max = val; return;
	}
	
	int mid = (tree[rt].left + tree[rt].right) >> 1;
	if(pos <= mid) update(pos, val, rt << 1);
	else update(pos, val, rt << 1 | 1);
	
	tree[rt].max = MAX(tree[rt<<1].max, tree[rt<<1|1].max);
}

int query(int left, int right, int rt)
{
	if(tree[rt].left == left && right == tree[rt].right){
		return tree[rt].max;
	}
	
	int mid = (tree[rt].left + tree[rt].right) >> 1;
	if(right <= mid) return query(left, right, rt << 1);
	else if(left > mid) 
		return query(left, right, rt << 1 | 1);
	return MAX(query(left, mid, rt << 1), query(mid+1, right, rt<<1|1));
}

int main()
{
	int N, M, i, m, n;
	char com[2];
	while(scanf("%d%d", &N, &M) == 2){
		for(i = 1; i <= N; ++i)
			scanf("%d", stu + i);
		build(1, N, 1);
		
		while(M--){
			scanf("%s%d%d", com, &m, &n);
			
			if(com[0] == 'U') update(m, n, 1);
			else printf("%d\n", query(m, n, 1));
		}
	}
	return 0;
}

TLE:：

#include <stdio.h>
#define MAX(a, b) a > b ? a : b
#define maxn 200002

struct Node{
    int lson, rson;
    int max;
} tree[maxn << 2];
int stu[maxn];

void build(int left, int right, int rt)
{
    tree[rt].lson = left; tree[rt].rson = right;
    if(left == right){
        tree[rt].max = stu[left]; return;
    }
    
    int mid = (left + right) >> 1;
    build(left, mid, rt << 1);
    build(mid + 1, right, rt << 1 | 1);
    
    tree[rt].max = MAX(tree[rt<<1].max, tree[rt<<1|1].max);
}

void update(int pos, int val, int rt)
{
    if(tree[rt].lson == tree[rt].rson){
        tree[rt].max = val; return;
    }
    
    int mid = (tree[rt].lson + tree[rt].rson) >> 1;
    if(pos <= mid) update(pos, val, rt << 1);
    else update(pos, val, rt << 1 | 1);
    
    tree[rt].max = MAX(tree[rt<<1].max, tree[rt<<1|1].max);
}

int query(int left, int right, int rt)
{
    if(tree[rt].lson == left && right == tree[rt].rson){
        return tree[rt].max;
    }
    
    int mid = (tree[rt].lson + tree[rt].rson) >> 1;
    if(right <= mid) return query(left, right, rt << 1);
    else if(left > mid) 
        return query(left, right, rt << 1 | 1);
    return MAX(query(left, mid, rt << 1), query(mid+1, right, rt<<1|1));
}

int main()
{
    int N, M, i, m, n;
    char com[2];
    while(scanf("%d%d", &N, &M) == 2){
        for(i = 1; i <= N; ++i)
            scanf("%d", stu + i);
        build(1, N, 1);
        
        while(M--){
            scanf("%s%d%d", com, &m, &n);
            
            if(com[0] == 'U') update(m, n, 1);
            else printf("%d\n", query(m, n, 1));
        }
    }
    return 0;
}

2015.1.28更新

#include <stdio.h>
#include <string.h>

#define maxn 200002
#define lson l, mid, rt << 1
#define rson mid + 1, r, rt << 1 | 1

int T[maxn << 2]; 
int N, M;

int max(int a, int b) { return a > b ? a : b; }

void pushUp(int rt) {
	T[rt] = max(T[rt<<1], T[rt<<1|1]);
}

void build(int l, int r, int rt) {
	if (l == r) {
		scanf("%d", &T[rt]);
		return;
	}

	int mid = l + r >> 1;
	build(lson);
	build(rson);

	pushUp(rt);
}

void update(int pos, int val, int l, int r, int rt) {
	if (l == r) {
		T[rt] = val; return;
	}

	int mid = l + r >> 1;
	if (pos <= mid) update(pos, val, lson);
	else update(pos, val, rson);

	pushUp(rt);
}

int query(int L, int R, int l, int r, int rt) {
	if (L == l && R == r) {
		return T[rt];
	}

	int mid = l + r >> 1;
	if (R <= mid) return query(L, R, lson);
	else if (L > mid) return query(L, R, rson);
	return max(query(L, mid, lson), query(mid + 1, R, rson));
}

int main() {
	freopen("stdin.txt", "r", stdin);
	int i, j, a, b;
	char com[2];
	while (~scanf("%d%d", &N, &M)) {
		build(1, N, 1);
		while (M--) {
			scanf("%s%d%d", com, &a, &b);
			if (*com == 'U') update(a, b, 1, N, 1);
			else printf("%d\n", query(a, b, 1, N, 1));
		}
	}
	return 0;
}