sqrt

Author: tanfanhua

src/com/blankj/easy/_0069/Solution.java

@@ -20,5 +20,57 @@ public int mySqrt(int x) {
     public static void main(String[] args) {
         Solution solution = new Solution();
         System.out.println(solution.mySqrt(10));
+        System.out.println(solution.sqrt(10));
+        System.out.println(solution.sqrt2(10));
+        System.out.println(solution.mySqrt(4));
+        System.out.println(solution.sqrt(4));
+        System.out.println(solution.sqrt2(4));
+        System.out.println(solution.mySqrt(3));
+        System.out.println(solution.sqrt(3));
+        System.out.println(solution.sqrt2(3));
+        System.out.println(solution.mySqrt(100));
+        System.out.println(solution.sqrt(100));
+        System.out.println(solution.sqrt2(100));
+
+    }
+
+    public int sqrt(int x) {
+        if (x <= 0) {
+            return 0;
+        }
+        for (int i = 0; i < x/2; i++) {
+            if (i * i <= x && (i + 1) * (i * 1) > x) {
+                return i;
+            }
+        }
+
+        return x/2;
+    }
+
+    public int sqrt2(int x) {
+        if (x <= 0) {
+            return 0;
+        }
+        int low = 0;
+        int high = x/2;
+        while (low <= high) {
+            int mid = (low + high) / 2;
+            if (mid*mid == x) {
+                return mid;
+            } else if (mid*mid < x) {
+                if (low == mid) {
+                    if (high * high > x) {
+                        return mid;
+                    } else {
+                        return high;
+                    }
+                }
+                low = mid;
+            } else {
+                high = mid;
+            }
+        }
+
+        return -1;
     }
 }