|
|
#include <algorithm>
|
|
|
#include <cstdio>
|
|
|
#include <cstring>
|
|
|
using namespace std;
|
|
|
|
|
|
const int N = 2e5 + 1000;
|
|
|
// 快读
|
|
|
int read() {
|
|
|
int x = 0, f = 1;
|
|
|
char ch = getchar();
|
|
|
while (ch < '0' || ch > '9') {
|
|
|
if (ch == '-') f = -1;
|
|
|
ch = getchar();
|
|
|
}
|
|
|
while (ch >= '0' && ch <= '9') {
|
|
|
x = (x << 3) + (x << 1) + (ch ^ 48);
|
|
|
ch = getchar();
|
|
|
}
|
|
|
return x * f;
|
|
|
}
|
|
|
// zkw线段树
|
|
|
int d[N << 2];
|
|
|
|
|
|
int n; // n个叶子节点
|
|
|
int q; // q个操作,区间查询或单点修改
|
|
|
int m; // m是指所有父节点们的个数
|
|
|
|
|
|
//单点修改并psuhup
|
|
|
void modify(int x, int c) {
|
|
|
d[m + x] = c;
|
|
|
for (int i = (m + x) >> 1; i; i >>= 1) d[i] = max(d[i << 1], d[i << 1 | 1]);
|
|
|
}
|
|
|
|
|
|
//构建重口味树
|
|
|
void built() {
|
|
|
memset(d, 0, sizeof d);
|
|
|
for (m = 1; m <= n + 1;) m <<= 1; // 强行开够（大于n）方便二进制访问叶节点
|
|
|
for (int i = 1; i <= n; i++) d[m + i] = read(); //初始值
|
|
|
for (int i = m; i; i--) d[i] = max(d[i << 1], d[i << 1 | 1]); //待所有叶子节点有值后，统一执行一次向上数据统计信息汇总
|
|
|
}
|
|
|
|
|
|
//区间查询
|
|
|
int query(int l, int r) {
|
|
|
int ans = -1;
|
|
|
// 闭区间改为开区间：l=l+m-1 : 将查询区间改为l-1, r=r+m+1 : 将查询区间改为r+1
|
|
|
// l^r^1 : 相当于判断l与r是否是兄弟节点
|
|
|
for (l = l + m - 1, r = r + m + 1; l ^ r ^ 1; l >>= 1, r >>= 1) {
|
|
|
if (~l & 1) ans = max(ans, d[l ^ 1]); // l % 2 == 0 左端点 是左儿子 max(右子树)，想像一下题解中0号端点（哨兵），肯定是%2=0
|
|
|
if (r & 1) ans = max(ans, d[r ^ 1]); // r % 2 == 1 右端点 是右儿子 max(左子树)，想像一下题解中1号端点，肯定是%2=1
|
|
|
}
|
|
|
return ans;
|
|
|
}
|
|
|
|
|
|
//方法重载，单点查询 [本题没有用到，用来做模板的]
|
|
|
int query(int x) {
|
|
|
return d[m + x]; //直接返回结果的zkw线段树节点值
|
|
|
}
|
|
|
|
|
|
int main() {
|
|
|
//文件输入输出
|
|
|
#ifndef ONLINE_JUDGE
|
|
|
freopen("HDU1754.in", "r", stdin);
|
|
|
#endif
|
|
|
char op[2];
|
|
|
while (~scanf("%d%d", &n, &q)) {
|
|
|
//构建zkw树
|
|
|
built();
|
|
|
|
|
|
while (q--) {
|
|
|
scanf("%s", op);
|
|
|
int l = read(), r = read();
|
|
|
if (op[0] == 'Q')
|
|
|
printf("%d\n", query(l, r));
|
|
|
else
|
|
|
modify(l, r);
|
|
|
}
|
|
|
}
|
|
|
return 0;
|
|
|
} |
