POJ 3264 Balanced Lineup (RMQ线段树)

/*3891ms,1420KB*/

#include <cstdio>
#include <algorithm>
using namespace std;
#define lson l, m, rt << 1
#define rson m + 1, r, rt << 1 | 1
#define root 1, n, 1
const int mx = 50000;

int minh[mx << 2], maxh[mx << 2], x;

inline void pushup(int rt)
{
	maxh[rt] = max(maxh[rt << 1], maxh[rt << 1 | 1]);
	minh[rt] = min(minh[rt << 1], minh[rt << 1 | 1]);
}

void build(int l, int r, int rt)
{
	if (l == r)
	{
		scanf("%d", &x);
		minh[rt] = maxh[rt] = x;
		return;
	}
	int m = (l + r) >> 1;
	build(lson);
	build(rson);
	pushup(rt);
}

int querymaxh(int ql, int qr, int l, int r, int rt)
{
	if (ql <= l && r <= qr)
	{
		return maxh[rt];
	}
	int maxh = 0, m = (l + r) >> 1;
	if (ql <= m) maxh = querymaxh(ql, qr, lson);
	if (m < qr) maxh = max(maxh, querymaxh(ql, qr, rson));
	return maxh;
}

int queryminh(int ql, int qr, int l, int r, int rt)
{
	if (ql <= l && r <= qr)
	{
		return minh[rt];
	}
	int minh = 1000000, m = (l + r) >> 1;
	if (ql <= m) minh = queryminh(ql, qr, lson);
	if (m < qr) minh = min(minh, queryminh(ql, qr, rson));
	return minh;
}

int main()
{
    int n,m,a,b;
	scanf("%d%d", &n, &m);
	build(root);
	while (m--)
	{
		scanf("%d%d", &a, &b);
		printf("%d\n", querymaxh(a, b, root) - queryminh(a, b, root));
	}
	return 0;
}