ways_to_cover.cpp

// A Dynamic Programming based C++ program to count number of ways 
// to cover a distance with 1, 2 and 3 steps 
#include<iostream> 
using namespace std; 
  
int printCountDP(int dist) 
{ 
    int count[dist+1]; 
  
    // Initialize base values. There is one way to cover 0 and 1 
    // distances and two ways to cover 2 distance 
    count[0]  = 1,  count[1] = 1,  count[2] = 2; 
  
    // Fill the count array in bottom up manner 
    for (int i=3; i<=dist; i++) 
       count[i] = count[i-1] + count[i-2] + count[i-3]; 
  
    return count[dist]; 
} 
  
// driver program 
int main() 
{ 
    int dist = 4; 
    cout << printCountDP(dist); 
    return 0; 
}