Update fixed-point solution

Author: imajinyun

src/leetcode/FixedPoint.php

@@ -0,0 +1,44 @@
+<?php
+
+declare(strict_types=1);
+
+namespace leetcode;
+
+class FixedPoint
+{
+    public static function fixedPoint(array $nums): int
+    {
+        if (empty($nums)) {
+            return 0;
+        }
+
+        foreach ($nums as $key => $val) {
+            if ($key === $val) {
+                return $key;
+            }
+        }
+
+        return -1;
+    }
+
+    public static function fixedPoint2(array $nums): int
+    {
+        if (empty($nums)) {
+            return 0;
+        }
+
+        [$low, $high] = [0, $nums[count($nums) - 1]];
+        while ($low <= $high) {
+            $mid = (int) ($low + ($high - $low) / 2);
+            if ($nums[$mid] === $mid) {
+                return $mid;
+            } elseif ($mid > $nums[$mid]) {
+                $low++;
+            } else {
+                $high--;
+            }
+        }
+
+        return -1;
+    }
+}

tests/leetcode/FixedPointTest.php

@@ -0,0 +1,23 @@
+<?php
+
+declare(strict_types=1);
+
+namespace leetcode\tests;
+
+use leetcode\FixedPoint;
+use PHPUnit\Framework\TestCase;
+
+class FixedPointTest extends TestCase
+{
+    public function testFixedPoint(): void
+    {
+        self::assertSame(3, FixedPoint::fixedPoint([-10, -5, 0, 3, 7]));
+        self::assertSame(-1, FixedPoint::fixedPoint([-10, -5, 3, 4, 7, 9]));
+    }
+
+    public function testFixedPoint2(): void
+    {
+        self::assertSame(3, FixedPoint::fixedPoint2([-10, -5, 0, 3, 7]));
+        self::assertSame(-1, FixedPoint::fixedPoint2([-10, -5, 3, 4, 7, 9]));
+    }
+}