1 #include <iostream>
 2 #include <cstdio>
 3 #include <algorithm>
 4 using namespace std;
 5 #define lowbit(a) (a&(-a))
 6 
 7 int n, m, t[500010], bas[500010];
 8 
 9 inline void update(int x, int k){
10     while(x <= n){
11         t[x] += k;
 
12         x += lowbit(x);
13     }
14 }
15 
16 inline int Sum(int x){
17     int ans = 0;
18     while(x){
19         ans += t[x];
20         x -= lowbit(x);
21     }
22     return ans;
23 }
24 
25 int main(void){
26     scanf("%d%d", &n, &m);
27     for(int i = 1; i <= n; ++i) scanf("
 
%d", bas+i);
28     while(m--){
29         int bs, x, y, k;
30         scanf("%d", &bs);
31         if (bs == 1) {
32             scanf("%d%d%d", &x, &y, &k);
33             update(x,k), update(y+1,-k);
34         }
35         else {
36             scanf("%d", &x);
37             printf("
 
%d\n", bas[x] + Sum(x));
38         }
39     }
40     return 0;
41 }

[模板]樹狀數組2