Update reverse-string-ii solution

Author: imajinyun

src/leetcode/ReverseStringII.php

@@ -12,8 +12,7 @@ public static function reverseStr(string $s, int $k): string
             return '';
         }
         $n = strlen($s);
-        [$m, $n] = [0, strlen($s)];
-        for (; $m < $n; $m += 2 * $k) {
+        for ($m = 0; $m < $n; $m += 2 * $k) {
             for ($i = $m, $j = min($m + $k - 1, $n - 1); $i < $j; $i++, $j--) {
                 $t = $s[$i];
                 $s[$i] = $s[$j];
@@ -23,4 +22,26 @@ public static function reverseStr(string $s, int $k): string
 
         return $s;
     }
+
+    public static function reverseStr2(string $s, int $k): string
+    {
+        if (empty($s) || $k <= 0) {
+            return '';
+        }
+        [$i, $n] = [0, strlen($s)];
+        while ($i < $n) {
+            $j = min($i + $k - 1, $n - 1);
+            $m = $j + $k + 1;
+            while ($i < $j) {
+                $t = $s[$i];
+                $s[$i] = $s[$j];
+                $s[$j] = $t;
+                $i++;
+                $j--;
+            }
+            $i = $m;
+        }
+
+        return $s;
+    }
 }

tests/leetcode/ReverseStringIITest.php

@@ -14,4 +14,10 @@ public function testReverseStr(): void
         self::assertSame('bacdfeg', ReverseStringII::reverseStr('abcdefg', 2));
         self::assertSame('bacd', ReverseStringII::reverseStr('abcd', 2));
     }
+
+    public function testReverseStr2(): void
+    {
+        self::assertSame('bacdfeg', ReverseStringII::reverseStr2('abcdefg', 2));
+        self::assertSame('bacd', ReverseStringII::reverseStr2('abcd', 2));
+    }
 }