Add valid-perfect-square solution

Author: pony

src/leetcode/ValidPerfectSquare.php

@@ -0,0 +1,42 @@
+<?php
+
+declare(strict_types=1);
+
+namespace leetcode;
+
+class ValidPerfectSquare
+{
+    public static function isPerfectSquare(int $num): bool
+    {
+        if ($num <= 0) {
+            return false;
+        }
+        [$low, $high] = [0, intdiv($num + 1, 2)];
+        while ($low <= $high) {
+            $mid = $low + intdiv($high - $low, 2);
+            if ($mid * $mid > $num) {
+                $high = $mid - 1;
+            } elseif ($mid * $mid < $num) {
+                $low = $mid + 1;
+            } else {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    public static function isPerfectSquare2(int $num): bool
+    {
+        if ($num <= 0) {
+            return false;
+        }
+        $i = $n = 1;
+        while ($n < $num) {
+            $i++;
+            $n = $i * $i;
+        }
+
+        return $n === $num;
+    }
+}

tests/leetcode/ValidPerfectSquareTest.php

@@ -0,0 +1,23 @@
+<?php
+
+declare(strict_types=1);
+
+namespace leetcode\tests;
+
+use PHPUnit\Framework\TestCase;
+use leetcode\ValidPerfectSquare;
+
+class ValidPerfectSquareTest extends TestCase
+{
+    public function testIsPerfectSquare(): void
+    {
+        self::assertTrue(ValidPerfectSquare::isPerfectSquare(16));
+        self::assertFalse(ValidPerfectSquare::isPerfectSquare(14));
+    }
+
+    public function testIsPerfectSquare2(): void
+    {
+        self::assertTrue(ValidPerfectSquare::isPerfectSquare2(16));
+        self::assertFalse(ValidPerfectSquare::isPerfectSquare2(14));
+    }
+}