hdu 1754 I hate it（线段树）

#include<iostream>#include<cstring>#include<cstdio>using namespace std;struct student{int left, mid, right;int max;}stu[800000];int score[200001];int max1, max2;void Create(int s, int e, int n){stu[n].left=s;stu[n].right=e;stu[n].mid=(s+e)/2;stu[n].max=0;if( e-s==1) return;Create(s, stu[n].mid, 2*n);Create(stu[n].mid, e, 2*n+1);}//左闭右开void Insert(int score, int i, int n){if( score>stu[n].max)stu[n].max=score;if(stu[n].right-stu[n].left==1) return;if(i<stu[n].mid) Insert(score, i, 2*n);//注意等号问题else if(i>=stu[n].mid) Insert(score, i, 2*n+1);}int Query(int s, int e, int n){if(stu[n].left==s && stu[n].right==e)return stu[n].max;if( e<=stu[n].mid) return Query(s, e, 2*n);else if( s>=stu[n].mid) return Query(s, e, 2*n+1);else{max1=Query(s, stu[n].mid, 2*n);max2= Query(stu[n].mid, e, 2*n+1);return max1>max2?max1:max2;}}int main(){int n, m, a, b, i;char c;while( scanf("%d %d", &n, &m)!= EOF){Create(1,n+1, 1);for(i=1; i<=n; i++){scanf("%d", score+i);Insert(score[i], i, 1);}while( m-- ){getchar();scanf("%c %d %d", &c, &a, &b);if( c=='Q')printf("%d\n", Query(a, b+1, 1));//因为是左闭右开， 因此b+1elseInsert(b, a, 1);}}}