1、题目
Given an integer array nums, find the sum of the elements between indices i and j (i ≤ j), inclusive.
Example:
Given nums = [-2, 0, 3, -5, 2, -1] sumRange(0, 2) -> 1 sumRange(2, 5) -> -1 sumRange(0, 5) -> -3
2、解答:累加和,注意向量的作用域
3、代码
C++代码
class NumArray { public: vector<int> num; NumArray(vector<int> nums) { for(int i=1;i<nums.size();i++) nums[i] += nums[i-1]; num = nums; } int sumRange(int i, int j) { if(i==0) return num[j]; return num[j] - num[i-1]; } };
python代码
class NumArray: def __init__(self, nums): """ :type nums: List[int] """ self.nums = nums def sumRange(self, i, j): """ :type i: int :type j: int :rtype: int """ return sum(self.nums[i:j+1])