[Algorithm] 9. Two Sum

Description

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].

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Solution

     vector<int> twoSum(vector<int>& nums, int target) {
         int i,j;

         // Loop for the first item in the array.
         for ( i=; i<nums.size(); i++){
             // Loop for the second item after the first item.
             for ( j=i+1; j<nums.size(); j++){
                 // Check if the sum equals to target.
                 if( (nums[i] + nums[j]) == target ){
                     return {i,j};
                 }
             }
         }

         return {-,-};
     }