HDU - 3074 - Multiply game （线段树-单点更新，区间求积）

题目传送：Multiply game

思路：简单线段树，单点更新，区间求积，这是上次选拔赛选的题，一看题就是线段树，不过当时线段树不太熟，没敢敲，现在看来居然如此轻松，不过注意这里有大量输出，用printf，居然在这里TLE了一次。。。

AC代码：

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <cmath>
#include <queue>
#include <stack>
#include <vector>
#include <map>
#include <set>
#include <deque>
#include <cctype>
#define LL long long
#define INF 0x7fffffff
#define MOD 1000000007
using namespace std;

const int maxn = 50005;
int T;
int n;
LL mu[maxn << 2];

void build(int l, int r, int rt) {
	if(l == r) {
		scanf("%I64d", &mu[rt]);
		return;
	}
	int mid = (l + r) >> 1;
	build(l, mid, rt << 1);
	build(mid + 1, r, rt << 1 | 1);
	mu[rt] = (mu[rt << 1] * mu[rt << 1 | 1]) % MOD;
}

LL query(int L, int R, int l, int r, int rt) {
	if(L <= l && r <= R) {
		return mu[rt];
	}
	LL ret = 1;
	int mid = (l + r) >> 1;
	if(mid >= L) ret = (ret * query(L, R, l, mid, rt << 1)) % MOD;
	if(mid + 1 <= R) ret = (ret * query(L, R, mid + 1, r, rt << 1 | 1)) % MOD;
	return ret;
}

void update(int p, int v, int l, int r, int rt) {
	if(l == r) {
		mu[rt] = v;
		return;
	}
	int mid = (l + r) >> 1;
	if(p <= mid) update(p, v, l, mid, rt << 1);
	else update(p, v, mid + 1, r, rt << 1 | 1);
	mu[rt] = (mu[rt << 1] * mu[rt << 1 | 1]) % MOD;
}

int main() {
	scanf("%d", &T);
	while(T --) {
		scanf("%d", &n);
		build(1, n, 1);
		int q;
		scanf("%d", &q);
		while(q --) {
			int op, a, b;
			scanf("%d %d %d", &op, &a, &b);
			if(op == 0) {
				LL ans = query(a, b, 1, n, 1);
				printf("%I64d\n", ans);
			}
			else if(op == 1) {
				update(a, b, 1, n, 1);
			}
		}
	}
	return 0;
}