poj 3264 RMQ 线段树

zkw式线段树解决RMQ问题，只需查询，不用更新，很简单，ps: 为什么C++比gcc快那么多啊？gcc提交3047ms，用C++

的话，只需1329ms。

 

#include <stdio.h>

#define DEBUG

#ifdef DEBUG
#define debug(...) printf( __VA_ARGS__) 
#else
#define debug(...)
#endif

#define MIN(a, b) (a) < (b) ? (a): (b)
#define MAX(a, b) (a) > (b) ? (a): (b)

#define inf 20000000
#define N 50001

struct tree_node
{
	int min, max;
};

struct tree_node tree[131072];
int cow[N];
int n, M;

int min_h, max_h;

void build_tree()
{
	int		i;

	for (M = 1; M < (n+2); M <<= 1);

	//存储数据的叶子节点
	for (i = 1; i <= n; i++) {
		tree[i+M].min = tree[i+M].max = cow[i];
	}
	//不用的叶子节点
	for (i = n+1; i%M != 1; i++) {
		tree[(i%M)+M].min = inf;
		tree[(i%M)+M].max = -1;
	}
	//分支节点
	for (i = M-1; i > 0 ; i--) {
		tree[i].min = MIN(tree[i<<1].min, tree[(i<<1)+1].min);
		tree[i].max = MAX(tree[i<<1].max, tree[(i<<1)+1].max);
	}
}

void query(int s, int t)
{
	max_h = -1;
	min_h = inf;

	for (s = s+M-1, t = t+M+1; (s^t) != 1; s >>= 1, t >>= 1) {
		if (~s&1) {
			max_h = MAX(max_h, tree[s^1].max);
			min_h = MIN(min_h, tree[s^1].min);
		}
		if (t&1) {
			max_h = MAX(max_h, tree[t^1].max);
			min_h = MIN(min_h, tree[t^1].min);
		}
	}
}

int main()
{
	int 	i, q, s, t;

	scanf("%d %d", &n, &q);
	for (i = 1; i <= n; i++) {
		scanf("%d", cow+i);
	}

	build_tree();

	while (q--) {
		scanf("%d %d", &s, &t);
		query(s, t);
		printf("%d\n", max_h-min_h);
	}

	return 0;
}