hdu 1166 线段树 单点更新 区间查询

很久没写线段树了，这段时间打算刷个线段树专题。这道题应该算是线段树的模版题了。

#include<iostream>
#define MAX_N 50005

using namespace std;

struct node
{
    int peo;
    int l,r;
}num[MAX_N*4];
int pp[MAX_N];

void built_tree(int l,int r,int count)
{
    num[count].l=l;
    num[count].r=r;
    if(l==r)
    {
        num[count].peo = pp[l];
        return ;
    }
    int mid = (l+r)/2;
    built_tree(l, mid, count*2);
    built_tree(mid+1, r, count*2+1);
    num[count].peo=num[count*2].peo+num[count*2+1].peo;
}
int query_peo(int l,int r,int count)
{
    if(num[count].l==l && num[count].r==r)
        return num[count].peo;
    int mid = (num[count].l+num[count].r)/2;
    if(r<=mid)
        return query_peo(l,r, count*2);
    else
        if(l>mid)
            return query_peo(l, r, count*2+1);
    else
        return query_peo(l, mid,count*2)+query_peo(mid+1, r, count*2+1);
}
 
void update_peo(int a,int b,int count)
{
    if(num[count].l==num[count].r && num[count].l==a)
    {
        num[count].peo+=b;
        return ;
    }
    int mid = (num[count].l+num[count].r)/2;
    if(a<=mid)
        update_peo(a, b, count*2);
    else
        if(a>mid)
            update_peo(a, b, count*2+1);
    num[count].peo=num[count*2].peo+num[count*2+1].peo;
}
int main()
{
    cin.sync_with_stdio(false);
    int t,con=1;
    cin>>t;
    while(t--)
    {
        int n;
        cin>>n;
        for(int i = 1; i <= n; i++)
        {
            cin>>pp[i];
        }
        built_tree(1, n, 1);
        string s;
        int a,b;
        cout<<"Case "<<con++<<":"<<endl;
        while(1)
        {
            cin>>s;
            if(s=="End")
                break;
            cin>>a>>b;
            if(s=="Query")
            {
                cout<<query_peo(a, b, 1)<<endl;
            }
            else
                if(s=="Add")
                {
                    update_peo(a, b, 1);
                }
            else
                if(s=="Sub")
                {
                    b*=-1;
                    update_peo(a, b, 1);
                }
        }
    }
    return 0;
}