Add #69 Sqrt(x) Java Solution

Author: mengxinayan

README-zh.md

@@ -433,7 +433,7 @@
 | 73 | [Set Matrix Zeroes](https://leetcode-cn.com/problems/set-matrix-zeroes/) | [Python3](./algorithm/python/73_set_matrix_zeroes.py), [Java](./algorithm/java/73_set_matrix_zeroes.java) | 中等 | 数组 |
 | 71 | [Simplify Path](https://leetcode-cn.com/problems/simplify-path/) | [Python3](./algorithm/python/71_simplify_path.py) | 中等 | 栈, 字符串 |
 | 70 | [Climbing Stairs](https://leetcode-cn.com/problems/climbing-stairs/) | [Python3](./algorithm/python/70_climbing_stairs.py), [Java](./algorithm/java/70_climbing_stairs.java) | 简单 | 动态规划 |
-| 69 | [Sqrt(x)](https://leetcode-cn.com/problems/sqrtx/) | [Python3](./algorithm/python/69_Sqrt(x).py) | 简单 | 数学, 二分查找 |
+| 69 | [Sqrt(x)](https://leetcode-cn.com/problems/sqrtx/) | [Python3](./algorithm/python/69_Sqrt(x).py), [Java](./algorithm/java/69_Sqrt(x).java) | 简单 | 数学, 二分查找 |
 | 67 | [Add Binary](https://leetcode-cn.com/problems/add-binary/) | [Python3](./algorithm/python/67_add_binary.py) | 简单 | 数学, 字符串 |
 | 66 | [Plus One](https://leetcode-cn.com/problems/plus-one/) | [Python3](./algorithm/python/66_plus_one.py), [Java](./algorithm/java/66_plus_one.java) | 简单 | 数组 |
 | 64 | [Minimum Path Sum](https://leetcode-cn.com/problems/minimum-path-sum/) | [Python3](./algorithm/python/64_minimum_path_sum.py) | 中等 | 数组, 动态规划 |

README.md

@@ -432,7 +432,7 @@ If you have any questions or advices, please discuss them in [Issues](https://gi
 | 73 | [Set Matrix Zeroes](https://leetcode.com/problems/set-matrix-zeroes/) | [Python3](./algorithm/python/73_set_matrix_zeroes.py), [Java](./algorithm/java/73_set_matrix_zeroes.java) | Medium | Array |
 | 71 | [Simplify Path](https://leetcode.com/problems/simplify-path/) | [Python3](./algorithm/python/71_simplify_path.py) | Medium | Stack, String |
 | 70 | [Climbing Stairs](https://leetcode.com/problems/climbing-stairs/) | [Python3](./algorithm/python/70_climbing_stairs.py), [Java](./algorithm/java/70_climbing_stairs.java) | Easy | Dynamic Programming |
-| 69 | [Sqrt(x)](https://leetcode.com/problems/sqrtx/) | [Python3](./algorithm/python/69_Sqrt(x).py) | Easy | Math, Binary Search |
+| 69 | [Sqrt(x)](https://leetcode.com/problems/sqrtx/) | [Python3](./algorithm/python/69_Sqrt(x).py), [Java](./algorithm/java/69_Sqrt(x).java) | Easy | Math, Binary Search |
 | 67 | [Add Binary](https://leetcode.com/problems/add-binary/) | [Python3](./algorithm/python/67_add_binary.py) | Easy | Math, String |
 | 66 | [Plus One](https://leetcode.com/problems/plus-one/) | [Python3](./algorithm/python/66_plus_one.py), [Java](./algorithm/java/66_plus_one.java) | Easy | Array |
 | 64 | [Minimum Path Sum](https://leetcode.com/problems/minimum-path-sum/) | [Python3](./algorithm/python/64_minimum_path_sum.py) | Medium | Array, Dynamic Programming |

algorithm/java/69_Sqrt(x).java

@@ -0,0 +1,43 @@
+class Solution {
+    public int mySqrt(int x) {
+        if (x == 0 || x == 1) {
+            return x;
+        }
+        int left = 1;
+        int right = x;
+        int ans = -1;
+        int mid;
+        while (left < right) {
+            mid = left + (right - left) / 2;
+
+            if (mid+1 <= x / (mid+1)) {
+                left = mid;
+            } else if (mid > x / mid) {
+                right = mid;
+            } else {
+                ans = mid;
+                break;
+            }
+        }
+        return ans;
+    }
+}
+
+/**
+ * This is my personal record of solving Leetcode Problems. 
+ * If you have any questions, please discuss them in [Issues](https://github.com/mengxinayan/leetcode/issues).
+ * Copyright (C) 2020-2021  mengxinayan
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */