Problem:
Range Sum Query

Write a program which manipulates a sequence A = {a1, a2, . . . , an} with the following operations:

add(i, x): add x to ai.

getSum(s, t): print the sum of as, as+1,...,at.

Note that the initial values of ai (i = 1, 2, . . . , n) are 0.

Input

n q
com1 x1 y1
com2 x2 y2
...
comq xq yq

In the first line, n (the number of elements in A) and q (the number of queries) are given. Then, q queries are given where com represents the type of queries. '0' denotes add(xi, yi) and '1' denotes getSum(xi, yi).

Output

For each getSum operation, print the sum in a line.

Constraints

1 ≤ n ≤ 100000

1 ≤ q ≤ 100000

If comi is 0, then 1 ≤ xi ≤ n, 0 ≤ yi ≤ 1000.

If comi is 1, then 1 ≤ xi ≤ n, 1 ≤ yi ≤ n.

Sample Input 1

3 5
0 1 1
0 2 2
0 3 3
1 1 2
1 2 2

Sample Output 1

3
2

Solution in C++ (judge verdict: Accepted)

#include <bits/stdc++.h>
using namespace std;

class BIT{
public:
  int n,bit[200010];
  BIT(){fill(bit,bit+200010,0);}
  void add(int i,int x){
    while(i<=n){
      bit[i]+=x;
      i+=i&-i;
    }
  }
  int sum(int i){
    int s=0;
    while(i>0){
      s+=bit[i];
      i-=i&-i;
    }
    return s;
  }
};

int main() {
  BIT b;
  int q;
  cin >> b.n >> q;
  while(q--) {
    int x,y,z;
    cin >> x >> y >> z;
    if(x) cout << b.sum(z)-b.sum(y-1) << endl;
    else b.add(y,z);
  }
  return 0;
}