树状数组模板

Posted 2021-01-15 hwy499

 HDU 1166（敌兵布阵）（树状数组 单点更新区间求和）

#include<iostream>
#include<cstring>
#include<cmath>
using namespace std;
#define lowbit(x) x & (-x)//lowbit函数
#define LL long long  
LL a[100005],n;
void updata(LL x,LL v) {//更新函数
    while(x<=n) {
        a[x]+=v;
        x+=lowbit(x);
    }
}
LL query(LL x) {//查询函数
    LL sum=0;
    while(x) {
        sum+=a[x];
        x-=lowbit(x);
    }
    return sum;
}
int main() {
    LL t;
    cin>>t;
    LL d=1;
    while(t--) {
        cout<<"Case "<<d<<":"<<endl;
        cin>>n;
        LL s;
        memset(a,0,sizeof(a));
        for(LL i=1; i<=n; i++) {
            cin>>s;
            updata(i,s);
        }
        string ss;
        int l,r;
        while(cin>>ss)
        {
            if(ss=="End"){
                break;
            } 
            cin>>l>>r;
            if(ss[0]==‘A‘) {
                updata(l,r);
            } else if(ss[0]==‘S‘) {
                updata(l,-r);
            } else {
                cout<<query(r)-query(l-1)<<endl;
            }
        }
        d+=1;
    }
    return 0;
}

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