add 680

Author: fishercoder1534

README.md

@@ -22,6 +22,7 @@ Your ideas/fixes/algorithms are more than welcome!
 
 |  #  |      Title     |   Solutions   | Time          | Space         | Difficulty  | Tag          | Notes
 |-----|----------------|---------------|---------------|---------------|-------------|--------------|-----
+|680|[Valid Palindrome II](https://leetcode.com/problems/valid-palindrome-ii/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_680.java) | O(n) | O(1) | Easy | String
 |676|[Implement Magic Dictionary](https://leetcode.com/problems/implement-magic-dictionary/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_676.java) | O(n^2) | O(n) | Medium |
 |674|[Longest Continuous Increasing Subsequence](https://leetcode.com/problems/longest-continuous-increasing-subsequence/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_674.java) | O(n^2) | O(1) | Easy | 
 |672|[Bulb Switcher II](https://leetcode.com/problems/bulb-switcher-ii/)|[Solution](../master/src/main/java/com/fishercoder/solutions/_672.java) | O(1) | O(1) | Medium | Math 

src/main/java/com/fishercoder/solutions/_680.java

@@ -0,0 +1,60 @@
+package com.fishercoder.solutions;
+
+/**
+ * 680. Valid Palindrome II
+ *
+ *  Given a non-empty string s, you may delete at most one character. Judge whether you can make it a palindrome.
+
+ Example 1:
+ Input: "aba"
+ Output: True
+
+ Example 2:
+ Input: "abca"
+ Output: True
+ Explanation: You could delete the character 'c'.
+
+ Note:
+ The string will only contain lowercase characters a-z. The maximum length of the string is 50000.
+
+ */
+public class _680 {
+    public static class Solution1 {
+        public boolean validPalindrome(String s) {
+            int left = 0;
+            int right = s.length() - 1;
+            int diff = 0;
+            while (left < right) {
+                if (s.charAt(left) != s.charAt(right)) {
+                    left++;
+                    diff++;
+                    if (diff > 1) {
+                        break;
+                    }
+                } else {
+                    left++;
+                    right--;
+                }
+            }
+            if (diff < 2) {
+                return true;
+            }
+            diff = 0;
+            left = 0;
+            right = s.length() - 1;
+            while (left < right) {
+                if (s.charAt(left) != s.charAt(right)) {
+                    right--;
+                    diff++;
+                    if (diff > 1) {
+                        break;
+                    }
+                } else {
+                    left++;
+                    right--;
+                }
+            }
+            return diff < 2;
+        }
+    }
+}

src/test/java/com/fishercoder/_680Test.java

@@ -0,0 +1,51 @@
+package com.fishercoder;
+
+import com.fishercoder.solutions._680;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class _680Test {
+    private static _680.Solution1 solution1;
+
+    @BeforeClass
+    public static void setup() {
+        solution1 = new _680.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        assertEquals(true, solution1.validPalindrome("aba"));
+    }
+
+    @Test
+    public void test2() {
+        assertEquals(true, solution1.validPalindrome("abcca"));
+    }
+
+    @Test
+    public void test3() {
+        assertEquals(true, solution1.validPalindrome("acbca"));
+    }
+
+    @Test
+    public void test4() {
+        assertEquals(false, solution1.validPalindrome("accbba"));
+    }
+
+    @Test
+    public void test5() {
+        assertEquals(true, solution1.validPalindrome("abdeeda"));
+    }
+
+    @Test
+    public void test6() {
+        assertEquals(true, solution1.validPalindrome("cbbcc"));
+    }
+
+    @Test
+    public void test7() {
+        assertEquals(false, solution1.validPalindrome("abc"));
+    }
+}