题目链接

#include <iostream>
#include <cstring>
#include <algorithm>

using namespace std;
const int N = 100010;
#define int long long
int tr[N],a[N],n,m;
int lowbit(int x)
{
    return x&-x;
}
void add(int x,int v)
{
    for(int i=x;i<=n;i+=lowbit(i))tr[i]+=v;
}
int sum(int x)
{
    int res=0;
    for(int i=x;i;i-=lowbit(i))res+=tr[i];
    return res;
}

signed main()
{
    cin>>n>>m;
    for(int i=1;i<=n;i++)
    {
        cin>>a[i];
        add(i,a[i]-a[i-1]);
    }
    while (m -- )
    {
        char c;
        cin>>c;
        if(c=='Q')
        {
            int x;
            cin>>x;
            cout<<sum(x)<<endl;
        }
        else
        {
            int l,r,v;
            cin>>l>>r>>v;
            add(l,v);
            add(r+1,-v);
        }
        
    }
}