two_sum.php

<?php

class Solution {

    /**
     * @param Integer[] $nums
     * @param Integer $target
     * @return Integer[]
     */
    function twoSum($nums, $target) {
        foreach ($nums as $i => $number) {
          $searchArea = $nums;
          unset($searchArea[$i]);
          $desired = $target - $number;
          if (!in_array($desired, $searchArea)) {
            continue;
          }
          return [$i, array_search($desired, $searchArea)];
        }
        return [];
    }

    function verify($nums, $target, $expected) {
        $result = $this->twoSum($nums, $target);
        if ($result != $expected) {
          echo "FAIL: Expected [" . implode(", ", $expected) . "] but got [" . implode(", ", $result) . "]\n";
        } else {
          echo "PASS: Expected [" . implode(", ", $expected) . "] and got [" . implode(", ", $result) . "]\n";
        }
    }
}

$a = new Solution();

// test cases

// basic
echo "=== Basic ===\n";
$a->verify([2, 7, 11, 15], 9, [0, 1]);
// not first two
echo "=== Not first two ===\n";
$a->verify([2, 7, 11, 15], 18, [1, 2]);
//negatives
echo "=== Negatives ===\n";
$a->verify([-2, -7, 11, 15], -9, [0, 1]);
// very large numbers
echo "=== Very large ===\n";
$a->verify([2147483647, 2147483647, 2147483647, 1], 2147483648, [0, 3]);
// very large numbers, but negative
echo "=== Very large negative ===\n";
$a->verify([-2147483647, -2147483000, -2147483641, -1], -2147483648, [0, 3]);
// impassable test case
echo "=== Impassable ===\n";
$a->verify([2147483647, 2147483647, 2147483647, 1], 2147483649, [0, 3]);