hdu 1754 I Hate It（最简单的线段树）

来源：互联网发布：布施知子作品集编辑：程序博客网时间：2024/05/16 14:34

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

没有任何变型，所以直接贴代码。

#include<iostream>#include<cstring>#include<cmath>#include<cstdio>#include<algorithm>#include <queue>using namespace std;const int maxn = 200005;const int oo = 0xfffffff;#define L_CHILD rt<<1, begin, mid#define R_CHILD rt<<1|1, mid + 1, endint segTree[maxn*4];void pushUp(int rt){    segTree[rt] = max(segTree[2*rt], segTree[2*rt+1]);}void build(int rt, int begin, int end){    if(begin == end) {        scanf("%d", segTree + rt);        return ;    }    int mid = begin + end >> 1;    build(L_CHILD);    build(R_CHILD);    pushUp(rt);}int query(int rt, int begin, int end, int left, int right){    if(left > end || right < begin) {        return -oo;    }    if(left <= begin && end <= right) {        return segTree[rt];    }    int mid = begin + end >> 1;    int p1 = query(L_CHILD, left, right);    int p2 = query(R_CHILD, left, right);    return max(p1, p2);}void update(int rt, int begin, int end, int idx, int val){    if(begin == end) {        segTree[rt] = val;        return ;    }    int mid = begin + end >> 1;    if(idx <= mid) {        update(L_CHILD, idx, val);    }    else {        update(R_CHILD, idx, val);    }    pushUp(rt);}int main(){    int n, m, x, y;    char ch;    while (scanf("%d%d", &n, &m) != EOF) {        build(1, 1, n);        while (m --) {            scanf(" %c%d%d", &ch, &x, &y);            if(ch == 'Q') {                printf("%d\n", query(1,1,n,x,y));            }            else {                update(1, 1, n, x, y);            }        }    }    return 0;}

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