Create 276. Paint Fence.java

Author: futurus

276. Paint Fence.java

@@ -0,0 +1,23 @@
+public class Solution {
+    public int numWays(int n, int k) {
+        if (n == 0 || k == 0 || (k == 1 && n >= 3)) {
+            return 0;
+        } else if (n == 1) {
+            return k;
+        } else {
+            int [] ways = new int[n+1];
+            ways[1] = k;
+            ways[2] = k*k;
+            
+            for (int i = 3; i <= n; i++) {
+                // Consider 2 cases:
+                // - if nth post is of different color from (n-1)th post
+                // - if nth post is of same color from (n-1)th post, which means 
+                //   (n-1)th post is of different color from (n-2)th post
+                ways[i] = ways[i-1] * (k-1) + ways[i-2] * (k-1); 
+            }
+        
+            return ways[n];
+        }
+    }
+}