2017-09-07 LeetCode_001 Two Sum

1. Two Sum

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].

Solutiom:

class Solution {

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public:

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

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        vector<int> ans;

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        int n = nums.size();

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        for (int i = 0; i < n; i++)

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            for (int j = i+1; j < n; j++)

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                if (nums[i]+nums[j] == target) {

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                    ans.push_back(i); ans.push_back(j); return ans;

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                }

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        return ans;

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    }

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};