http://acm.hdu.edu.cn/showproblem.php?pid=1754


模板。


/*1062ms,2284KB*/

#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 = 200000;

int maxs[mx << 2];

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

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

void update(int p, int s, int l, int r, int rt)
{
	if (l == r)
	{
		maxs[rt] = s;
		return;
	}
	int m = (l + r) >> 1;
	if (p <= m) update(p, s, lson);
	else update(p, s, rson);
	pushup(rt);
}

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

int main()
{
	int n, m, a, b;
	char c;
	while (~scanf("%d%d", &n, &m))
	{
		build(root);
		while (m--)
		{
			getchar();
			scanf("%c%d%d", &c, &a, &b);
			if (c == 'U') update(a, b, root);
			else printf("%d\n", query(a, b, root));
		}
	}
	return 0;
}