HDU1754线段树

来源：互联网发布：雅思7分有多难知乎编辑：程序博客网时间：2024/06/02 04:26
#include<iostream>#include<cstdio>using namespace std;struct node{      int s;      int l,r;  };  struct node tree[2000100];  int a[200010];  int create_tree(int h,int x,int y){//建树     int mid=(x+y)/2;//中间     tree[h].l=x;tree[h].r=y;     if(x==y){//如果左右范围相等     tree[h].s=a[x];    return tree[h].s;}int a=create_tree(2*h,x,mid);//向两边分开递归 int b=create_tree(2*h+1,mid+1,y);tree[h].s=a>b?a:b;    return tree[h].s;}int Q(int h,int x,int y){//询问     if(y<tree[h].l || x>tree[h].r)//如果需要查询的范围不在原来的范围内          return 0;      if(x<=tree[h].l && y>=tree[h].r)//如果需要查询的范围刚好匹配          return tree[h].s;      int a=Q(2*h,x,y);//向两侧分别递归      int b=Q(2*h+1,x,y);        return a>b?a:b;;}int U(int h,int x){//更新          if(x<tree[h].l || x>tree[h].r)          return tree[h].s;      if(tree[h].l==tree[h].r){          tree[h].s=a[tree[h].l];          return tree[h].s;      }      int a=U(2*h,x);      int b=U(2*h+1,x);      tree[h].s=a>b?a:b;      return tree[h].s;     }int main(){int i,j,k,m,n,x,y;while(scanf("%d%d",&n,&m)!=EOF){    for(i=1;i<=n;i++)scanf("%d",&a[i]);    create_tree(1,1,n);    for(i=1;i<=m;i++){          char c;            getchar();              scanf("%c%d%d",&c,&x,&y);             if(c=='Q'){                  cout<<Q(1,x,y)<<endl;              }else{                   a[x]=y;                  U(1,x);              }          }  }return 0;}
1 0