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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
Note:
前缀和的应用，很简单。
class NumArray { public: int n; vector<int> s; NumArray(vector<int> &nums) { n = nums.size(); if(n==0)return; s.push_back(nums[0]); for(int i=1;i<n;i++){ s.push_back(s.back()+nums[i]); } } int sumRange(int i, int j) { if(i>j)return 0; if(i==0) return s[j]; return s[j]-s[i-1]; } }; // Your NumArray object will be instantiated and called as such: // NumArray numArray(nums); // numArray.sumRange(0, 1); // numArray.sumRange(1, 2);
leetcode 303. Range Sum Query - Immutable（前缀和）
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原文地址：http://www.cnblogs.com/zywscq/p/5408424.html
