fd

Author: dingjikerbo

solution/src/main/java/com/inuker/solution/ReverseInteger.java

@@ -6,20 +6,6 @@
 
 public class ReverseInteger {
 
-    // 耗时43ms
-    public int reverse(int x) {
-        long y = x;
-        int sign = y > 0 ? 1 : -1;
-        y = y > 0 ? y : -y;
-        String s = String.valueOf(y);
-        s = new StringBuilder(s).reverse().toString();
-        y = Long.valueOf(s) * sign;
-        if (y > Integer.MAX_VALUE || y < Integer.MIN_VALUE) {
-            return 0;
-        }
-        return (int) y;
-    }
-
     // 耗时40ms
     public int reverse2(int x) {
         long y = x, r = 0;

test/src/main/java/com/inuker/test/main.java

@@ -35,4 +35,17 @@ public static void main(String[] args) {
             System.out.print(n + " ");
         }
     }
+
+    public int reverse(int x) {
+        int sign = x > 0 ? 1 : -1;
+        long y = Math.abs(x), z = 0;
+        for ( ; y > 0; y /= 10) {
+            z = z * 10 + y % 10;
+        }
+        z *= sign;
+        if (z > Integer.MAX_VALUE || z < Integer.MIN_VALUE) {
+            throw new IllegalStateException();
+        }
+        return (int) z;
+    }
 }