Leetcode 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].

Java實現：

public class Solution {
    public int[] twoSum(int[] nums, int target) {
        HashMap<Integer,Integer> map=new HashMap<Integer,Integer>();
        int result[]=new int[2];
        for(int i=0;i<nums.length;i++){
            int num=target-nums[i];
            if(map.containsKey(num)){
                result[0]=map.get(num);
                result[1]=i;
                return result;
            }
            map.put(nums[i],i);
        }
        return result;
    }
}

PHP實現：

<?php
function twoSum($nums,$target){
    $result=array();
    foreach ($nums as $key=>$value){
        $num=$target-$nums[$key];
        if ($i=array_search($num,$nums)){
            $result[0]=$key;
            $result[1]=$i;
            return $result;
        }
    }
}

print_r(twoSum(array(7,3,4,7),7));