Merge pull request #109 from Shubh-k04/patch-3

Adding interview question "Perfect Square"

Java/Algorithm/PerfectSquares.java

@@ -0,0 +1,28 @@
+/*
+Given an integer n, return the least number of perfect square numbers that sum to n.
+
+A perfect square is an integer that is the square of an integer; in other words, it is the product of some integer with itself. For example, 1, 4, 9, and 16 are perfect squares while 3 and 11 are not.
+*/
+
+public class PerfectSquares 
+{
+    public int numSquares(int n)
+    {
+    	if(n<=3)
+    		return n;
+    	int[] dp= new int[n+1];
+    	dp[0]=0; dp[1]=1; dp[2]=2; dp[3]=3;
+    	for(int i=4; i<=n; i++)
+    	{
+    		dp[i]=i;
+    		for(int x=1; x<= Math.ceil(Math.sqrt(i)); x++)
+    		{
+    			int temp= x*x;
+    			if(temp>i) break;
+    			else
+    				dp[i]= Math.min(dp[i], 1+dp[i-temp]);
+    		}
+    	}
+    	return dp[n];
+    }
+}