works/solutions/cpp/303.cpp


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26

#include <vector>

using std::vector;

class NumArray
{
private:
    vector<int> prefix_sums;

public:
    NumArray(vector<int> &nums)
    {
        prefix_sums.push_back(0);
        int sum = 0;
        for (auto num : nums)
        {
            sum += num;
            prefix_sums.push_back(sum);
        }
    }

    int sumRange(int i, int j)
    {
        return prefix_sums[j + 1] - prefix_sums[i];
    }
};