Create PaintingtheFence.cpp

PaintingtheFence.cpp

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+// C++ program for Painting Fence Algorithm
+// optimised version
+
+#include <bits/stdc++.h>
+using namespace std;
+
+// Returns count of ways to color k posts
+long countWays(int n, int k)
+{
+	long dp[n + 1];
+	memset(dp, 0, sizeof(dp));
+	long long mod = 1000000007;
+
+	dp[1] = k;
+	dp[2] = k * k;
+
+	for (int i = 3; i <= n; i++) {
+		dp[i] = ((k - 1) * (dp[i - 1] + dp[i - 2])) % mod;
+	}
+
+	return dp[n];
+}
+
+// Driver code
+int main()
+{
+	int n = 3, k = 2;
+	cout << countWays(n, k) << endl;
+	return 0;
+}