[LeetCode] Two Sum

Given an array of integers, find two numbers such that they add up to a specific target number. The function twoSum should return indices of the two numbers such that they add up to the targe
Given an array of integers, find two numbers such that they add up to a specific target number.

The function twoSum should return indices of the two numbers such that they add up to the target, where index1 must be less than index2. Please note that your returned answers (both index1 and index2) are not zero-based.

You may assume that each input would have exactly one solution.

Input: numbers={2, 7, 11, 15}, target=9
Output: index1=1, index2=2

/*****************************************************************************

 * @COPYRIGHT NOTICE

 * @Copyright (c) 2015, 楚兴

 * @All rights reserved

 * @Version : 1.0

 * @Author : 楚兴

 * @Date : 2015/2/5 13:40

 * @Status : Accepted

 * @Runtime : 22 ms

*****************************************************************************/

#include iostream 

#include vector 

#include algorithm 

using namespace std;

class Solution {

public:

 vector int twoSum(vector int numbers, int target) {

 vector int indices;

 vector int temp(numbers);

 sort(numbers.begin(),numbers.end());

 for (int i = 0; i numbers.size() - 1; i++)

 for (int j = i + 1; j numbers.size(); j++)

 if (numbers[i] + numbers[j] == target)

 int n1 = find(temp,numbers[i]);

 int n2 = find(temp,numbers[j], n1 - 1);

 if (n1 n2)

 indices.push_back(n1);

 indices.push_back(n2);

 else

 indices.push_back(n2);

 indices.push_back(n1);

 return indices;

 if (numbers[i] + numbers[j] target)

 break;

private:

 int find(vector int num, int n, int flag = -1)

 for (int i = 0; i num.size(); i++)

 if (i == flag)

 continue; //不能和前一个点序号相同

 if (num[i] == n)

 return i + 1;

int main()

 vector int nums;

 nums.push_back(2);

 nums.push_back(7);

 nums.push_back(11);

 nums.push_back(14);

 Solution s;

 vector int indices = s.twoSum(nums,9);

 return 0;

}

// Runtime: 28 ms

class Solution {

public:

 vector int twoSum(vector int nums, int target) {

 unordered_map int, int mymap;

 vector int indices;

 for (int i = 0; i nums.size(); i++)

 if (mymap.find(target - nums[i]) != mymap.end())

 indices.push_back(mymap[target-nums[i]] + 1);

 indices.push_back(i + 1);

 else

 mymap[nums[i]] = i;

 return indices;

};

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