HDU 1754I Hate It（线段树）

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中文题目就不多说意思了大概是让你求一个区间的最值问题无情套一发模板

#include <iostream>#include<cstdio>#include<algorithm>#include<cstring>#define lson l,m,rt<<1#define rson m+1,r,rt<<1|1using namespace std;const int maxn = 200005;int Max[maxn << 2];void Pushup(int rt){    Max[rt] = max(Max[rt<<1] , Max[rt<<1|1]);}void build(int l,int r,int rt){    if(l == r){        scanf("%d",&Max[rt]);        return ;    }    int m = (l + r) >> 1;    build(lson);    build(rson);    Pushup(rt);}void Update(int L,int c,int l,int r,int rt){    if(l == r){        Max[rt] = c;        return ;    }    int m = (l + r) >> 1;    if(L <= m) Update(L , c, lson);    else Update(L , c, rson);    Pushup(rt);}int query(int L,int R,int l,int r,int rt){    if(L <= l && r <= R){        return Max[rt];    }    int m = (l + r) >> 1;    int ret = -1;    if(L <= m)ret = max (ret , query(L , R, lson));    if(R > m)ret = max (ret , query(L , R, rson));    return ret;}int main(){    int N,M,a,b;    char op[5];    while(~scanf("%d%d",&N,&M)){        build(1 , N, 1);        for (int i = 0; i < M; i ++) {            scanf("%s",op);            if(op[0] == 'U'){               scanf("%d%d",&a,&b);               Update(a , b, 1, N, 1);            }            else {                scanf("%d%d",&a,&b);                printf("%d\n",query(a , b, 1, N, 1));            }        }    }    return 0;}

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