Add Solution2.java for 0202.Happy Number

Author: huaxu1024

solution/0202.Happy Number/Solution2.java

@@ -0,0 +1,22 @@
+class Solution {
+    // fast slow point
+    public boolean isHappy(int n) {
+        int fast = n;
+        int slow = n;
+        do {
+            slow = squareSum(slow);
+            fast = squareSum(fast);
+            fast = squareSum(fast);
+        } while (slow != fast);
+        return fast == 1 ? true : false;
+    }
+
+    private int squareSum(int m) {
+        int squaresum = 0;
+        while (m != 0) {
+            squaresum += (m%10) * (m%10);
+            m /= 10;
+        }
+        return squaresum;
+    }
+}