Sqrt

Change-Id: I1fcca7720537bd8777b820629991c01ee03d4f98

Author: applewjg

Sqrt(x).java

@@ -0,0 +1,27 @@
+/*
+ Author:     King, [email protected]
+ Date:       Apr 18, 2013
+ Problem:    Sqrt(x)
+ Difficulty: Easy
+ Source:     http://leetcode.com/onlinejudge#question_69
+ Notes:
+ Implement int sqrt(int x).
+ Compute and return the square root of x.
+
+ Solution: 1. Binary search in range [0, x / 2 + 1].
+           2. Newton iteration method. x(i+1) = (x(i) + n/x(i)) / 2.
+ See my blog (http://www.cnblogs.com/AnnieKim/archive/2013/04/18/3028607.html) for more explanation (in Chinese).
+ */
+public class Solution {
+    public int sqrt(int x) {
+        int left = 1, right = x/2;
+        if(x<2) return x;
+        while (left <= right) {
+            int mid = (left + right)/2;
+            if (x/mid == mid) return mid;
+            if (x/mid > mid) left = mid + 1;
+            else right = mid - 1;
+        }
+        return right;
+    }
+}