add exercise tribonacci

C++/Language/tribonacci.cpp

@@ -0,0 +1,31 @@
+/* 
+        Author : Johnny Quintero
+        Date : Date format 14/10/2021
+        Description : C++ program to calculate the tribonacci of a number with programming dynamic
+*/
+ #include <bits/stdc++.h>
+    using namespace std;
+    #define ll long long
+    const ll MOD = 1000000007;
+    ll dp[100000+1]; // table of memorization of answers
+
+    //Function to calculate the tribonacci with programming dynamic
+    void tribonaci(){
+    	dp[1] = 0;
+    	dp[2] = 0;
+    	dp[3] = 1;
+    	for(int i = 4; i <= 100000; i++){
+    		dp[i] = ( dp[i-1]%MOD + dp[i-2]%MOD + dp[i-3]%MOD ) %MOD;
+    	}
+    }
+
+
+    int main() {
+        // initialize the memorization table to zero
+    	memset(dp,0,sizeof(dp));
+    	tribonaci();
+    	ll n;
+    	while(cin>>n){
+    		cout<< dp[n] <<endl;
+    	}
+    }