标签：hdoj1754

I Hate It

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

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。”

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;
}

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HDOJ1754 I Hate It 【线段树】

标签：hdoj1754

原文地址：http://blog.csdn.net/chang_mu/article/details/37502903