leetcode303--区域和检索

1. 题意

实现一个查询区间和的类

区域和检索

2. 题解

简单前缀和

class NumArray {
    vector<int> prefix;
public:
    NumArray(vector<int>& nums) {
        int sum = 0;
        for(auto &num: nums) {
            prefix.push_back(sum);
            sum += num;
        }
        prefix.push_back(sum);
    }
    
    int sumRange(int left, int right) {
        return prefix[right + 1] - prefix[left];
    }
};

/**
 * Your NumArray object will be instantiated and called as such:
 * NumArray* obj = new NumArray(nums);
 * int param_1 = obj->sumRange(left,right);
 */