树状数组（区间修改单点查询）洛谷：树状数组2

模版和单点修改区间查询差不多

树状数组（单点修改区间查询）

https://blog.csdn.net/johnwayne0317/article/details/84927585

然后用到了差分数组

https://blog.csdn.net/johnwayne0317/article/details/84928568

代码

#include 
using namespace std;
int tree[1000000];
int cha[1000000];
int m,n;
int lowbit(int x){
    return x&(-x);
}
void add(int x,int k){
    while(x<=n){
        tree[x]+=k;
        x+=lowbit(x);
    }
}

int query(int x){
    int ans=0;
    while(x>0){
        ans+=tree[x];
        x-=lowbit(x);
    }
    return ans;
}
int main(int argc, const char * argv[]) {

    cin>>n>>m;
    memset(cha,0,sizeof(cha));
    memset(tree,0,sizeof(tree));
    for(int i=1;i<=n;i++){
        cin>>cha[i];
        add(i,cha[i]-cha[i-1]);
    }
    for(int i=0;i<m;i++){
        int w;
        cin>>w;
        if(w==1){
            int x,y,k;
            cin>>x>>y>>k;
            add(x,k);
            add(y+1,-k);
        }else{
            int x;
            cin>>x;
            cout<<query(x)<<endl;
        }
    }
    return 0;
}