LeetCode:Range Sum Query - Immutable

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Given nums = [-2, 0, 3, -5, 2, -1]

sumRange(0, 2) -> 1
sumRange(2, 5) -> -1
sumRange(0, 5) -> -3

c++ code:

class NumArray {
public:
    NumArray(vector<int> &nums) {
        sums.push_back(0);
        for(int i=0;i<nums.size();i++) {
            sums.push_back(sums.back() + nums[i]);
        }
    }

    int sumRange(int i, int j) {
        return sums[j + 1] - sums[i];
    }
private:
    vector<int> sums;
};


// Your NumArray object will be instantiated and called as such:
// NumArray numArray(nums);
// numArray.sumRange(0, 1);
// numArray.sumRange(1, 2);

LeetCode:Range Sum Query - Immutable

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原文地址：http://blog.csdn.net/itismelzp/article/details/51378075