refactor 1493

Author: fishercoder1534

src/main/java/com/fishercoder/solutions/_1493.java

@@ -39,4 +39,37 @@ public int longestSubarray(int[] nums) {
             return longest;
         }
     }
+
+    public static class Solution2 {
+        /**
+         * Sliding window solution
+         * Credit: https://leetcode.com/problems/longest-subarray-of-1s-after-deleting-one-element/discuss/708112/JavaC%2B%2BPython-Sliding-Window-at-most-one-0
+         * <p>
+         * we initialize k to be one, meaning we could have at most one zero in the sliding window
+         * i is the left pointer
+         * j is the right pointer
+         * when j encounters a zero, we'll decrement k by one;
+         * and once k becomes negative, that means we have more than one zeroes in the sliding window,
+         * so we'll have to move left pointer to the right until k becomes not negative;
+         * along this process, we use result to hold the max length of this sliding window
+         */
+        public int longestSubarray(int[] nums) {
+            int i = 0;
+            int k = 1;
+            int result = 0;
+            for (int j = 0; j < nums.length; j++) {
+                if (nums[j] == 0) {
+                    k--;
+                }
+                while (k < 0) {
+                    if (nums[i] == 0) {
+                        k++;
+                    }
+                    i++;
+                }
+                result = Math.max(result, j - i);
+            }
+            return result;
+        }
+    }
 }

src/test/java/com/fishercoder/_1493Test.java

@@ -8,11 +8,13 @@
 
 public class _1493Test {
     private static _1493.Solution1 solution1;
+    private static _1493.Solution2 solution2;
     private static int[] nums;
 
     @BeforeClass
     public static void setup() {
         solution1 = new _1493.Solution1();
+        solution2 = new _1493.Solution2();
     }
 
     @Test
@@ -21,4 +23,16 @@ public void test1() {
         assertEquals(3, solution1.longestSubarray(nums));
     }
 
+    @Test
+    public void test2() {
+        nums = new int[]{1, 1, 0, 1};
+        assertEquals(3, solution2.longestSubarray(nums));
+    }
+
+    @Test
+    public void test3() {
+        nums = new int[]{0, 1, 1, 1, 0, 1, 1, 0, 1};
+        assertEquals(5, solution2.longestSubarray(nums));
+    }
+
 }