0069. Sqrt(x)

coderbean · coderbean · commit 1b0de32a9658 · 2019-07-20T17:01:01.000+08:00
diff --git a/markdown/0069. Sqrt(x).md b/markdown/0069. Sqrt(x).md
@@ -0,0 +1,57 @@
+### [69\. Sqrt(x)](https://leetcode.com/problems/sqrtx/)
+
+Difficulty: **Easy**
+
+
+Implement `int sqrt(int x)`.
+
+Compute and return the square root of _x_, where _x_ is guaranteed to be a non-negative integer.
+
+Since the return type is an integer, the decimal digits are truncated and only the integer part of the result is returned.
+
+**Example 1:**
+
+```
+Input: 4
+Output: 2
+```
+
+**Example 2:**
+
+```
+Input: 8
+Output: 2
+Explanation: The square root of 8 is 2.82842..., and since 
+             the decimal part is truncated, 2 is returned.
+```
+
+
+#### Solution
+
+Language: **Java**
+
+```java
+class Solution {
+    public int mySqrt(int x) {
+        int left = 0;
+        int right = x;
+        int medium = (left + right) / 2;
+        while (left <= right) {
+            if (medium == 0) {
+                return right;
+            }
+            int target = x / medium;
+            if (medium == target || medium == target + 1) {
+                return target;
+            } else if (target < medium) {
+                right = medium;
+            } else if (target > medium - 1) {
+                left = medium + 1;
+            }
+            medium = (left + right) / 2;
+        }
+        return 0;
+    }
+}
+```
+![](https://raw.githubusercontent.com/PicGoBed/PicBed/master/20190720170020.png)
diff --git a/src/main/java/leetcode/_69_/Main.java b/src/main/java/leetcode/_69_/Main.java
@@ -0,0 +1,15 @@
+package leetcode._69_;
+
+/**
+ * Created by zhangbo54 on 2019-03-04.
+ */
+public class Main {
+    public static void main(String[] args) {
+        Solution solution = new Solution();
+        System.out.println( solution.mySqrt(2147395599));
+        System.out.println( solution.mySqrt(0));
+        System.out.println( solution.mySqrt(1));
+        System.out.println( solution.mySqrt(6));
+    }
+}
+
diff --git a/src/main/java/leetcode/_69_/Solution.java b/src/main/java/leetcode/_69_/Solution.java
@@ -0,0 +1,24 @@
+package leetcode._69_;
+
+class Solution {
+    public int mySqrt(int x) {
+        int left = 0; // 二分法
+        int right = x;
+        int medium = (left + right) / 2;
+        while (left <= right) {
+            if (medium == 0) {
+                return right;
+            }
+            int target = x / medium;
+            if (medium == target || medium == target + 1) {
+                return target;
+            } else if (target < medium) {
+                right = medium;
+            } else if (target > medium - 1) {
+                left = medium + 1;
+            }
+            medium = (left + right) / 2;
+        }
+        return 0;
+    }
+}
diff --git a/src/main/java/leetcode/_69_/solution.md b/src/main/java/leetcode/_69_/solution.md
@@ -0,0 +1,57 @@
+### [69\. Sqrt(x)](https://leetcode.com/problems/sqrtx/)
+
+Difficulty: **Easy**
+
+
+Implement `int sqrt(int x)`.
+
+Compute and return the square root of _x_, where _x_ is guaranteed to be a non-negative integer.
+
+Since the return type is an integer, the decimal digits are truncated and only the integer part of the result is returned.
+
+**Example 1:**
+
+```
+Input: 4
+Output: 2
+```
+
+**Example 2:**
+
+```
+Input: 8
+Output: 2
+Explanation: The square root of 8 is 2.82842..., and since 
+             the decimal part is truncated, 2 is returned.
+```
+
+
+#### Solution
+
+Language: **Java**
+
+```java
+class Solution {
+    public int mySqrt(int x) {
+        int left = 0;
+        int right = x;
+        int medium = (left + right) / 2;
+        while (left <= right) {
+            if (medium == 0) {
+                return right;
+            }
+            int target = x / medium;
+            if (medium == target || medium == target + 1) {
+                return target;
+            } else if (target < medium) {
+                right = medium;
+            } else if (target > medium - 1) {
+                left = medium + 1;
+            }
+            medium = (left + right) / 2;
+        }
+        return 0;
+    }
+}
+```
+![](https://raw.githubusercontent.com/PicGoBed/PicBed/master/20190720170020.png)
