-08-28剑指 Offer 57 - II. 和为s的连续正数序列

双指针

1）终止条件target = = sum；

2）target > sum 的时候，left++；

3）target < sum 的时候，right++；

5）sum = （【right + left】【right - left + 1】）/ 2

等差数列求和

class Solution {public:vector<vector<int>> findContinuousSequence(int target) {vector<vector<int>> ret;vector<int> helper;int left = 1,right = 2;while(left < right){int sum = (right + left)*(right - left + 1) / 2;if(sum == target){helper.clear();for(int i = left;i <= right;i++){helper.push_back(i);}ret.push_back(helper);left++;}else if(sum < target){right++;}else left++;}return ret;}};