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Maintenant, vous regardez: 1. Two Sum

1. Two Sum

Submitted by elyzium on Thu, 2019-07-18 15:25

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

  1. Given nums = [2, 7, 11, 15], target = 9,
  2. Because nums[0] + nums[1] = 2 + 7 = 9,
  3. return [0, 1].

Structure

  1. class Solution {
  2.  
  3.     /**
  4.      * @param Integer[] $nums
  5.      * @param Integer $target
  6.      * @return Integer[]
  7.      */
  8.     function twoSum($nums, $target) {
  9.         //code goes here
  10.     }
  11. }

One Solution:

  1. class Solution {
  2.     /**
  3.      * @param Integer[] $nums
  4.      * @param Integer $target
  5.      * @return Integer[]
  6.      */
  7.     function twoSum(array $nums,  int $target) : array {
  8.         $map = [];
  9.         for ($i = 0; $i < count($nums); $i++) {
  10.             $map[$nums[$i]] = $i;
  11.         }
  12.         for ($i = 0; $i < count($nums); $i++) {
  13.             $complement = $target - $nums[$i];
  14.             if (array_key_exists($complement, $map) && $map[$complement] != $i) {
  15.                 return [$i, $map[$complement] ];
  16.             }
  17.         }
  18.         throw new IllegalArgumentException("No two sum solution");      
  19.     }
  20. }
  21.  
  22. $instance = new Solution();
  23.  
  24. $result = $instance->twoSum([2, 7, 11, 15, 20], 26);
  25.  
  26. print_r($result);

Output:

  2. (
  3.     [0] => 2
  4.     [1] => 3
  5. )

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