1. Two Sum（LeetCode）

Given an array of integers, return indices of the two numbers such that they add up to a specific target.

You may assume that each input would have exactly one solution, and you may not use the same element twice.

Example:

Given nums = [2, 7, 11, 15], target = 9,

Because nums[0] + nums[1] = 2 + 7 = 9,
return [0, 1].

 1 class Solution {
 2 public:
 3     vector<int> twoSum(vector<int>& nums, int target) {
 4         vector<int> num=nums;
 5         sort(num.begin(), num.end());
 6         int len = num.size();
 7         int left = 0;
 8         int right = len - 1;
 9         while (left < right)
10         {
11             if ((num[left] + num[right])>target)
12                 right--;
13             else
14             if ((num[left] + num[right]) < target)
15                 left++;
16             else
17                 break;
18         }
19         vector<int> vet;
20         for(int i=0;i<len;i++)
21         {
22             if(nums[i]==num[left]||nums[i]==num[right])
23                vet.push_back(i);
24         }
25        
26         return vet;
27     }
28 };