how to find the number of cycles in a graph C++

// CPP Program to count cycles of length n 
// in a given graph. 
#include <bits/stdc++.h> 
using namespace std; 
  
// Number of vertices 
const int V = 5; 
  
void DFS(bool graph[][V], bool marked[], int n, 
               int vert, int start, int &count) 
{ 
    // mark the vertex vert as visited 
    marked[vert] = true; 
  
    // if the path of length (n-1) is found 
    if (n == 0) { 
  
        // mark vert as un-visited to make 
        // it usable again. 
        marked[vert] = false; 
  
        // Check if vertex vert can end with 
        // vertex start 
        if (graph[vert][start]) 
        { 
            count++; 
            return; 
        } else
            return; 
    } 
  
    // For searching every possible path of 
    // length (n-1) 
    for (int i = 0; i < V; i++) 
        if (!marked[i] && graph[vert][i]) 
  
            // DFS for searching path by decreasing 
            // length by 1 
            DFS(graph, marked, n-1, i, start, count); 
  
    // marking vert as unvisited to make it 
    // usable again. 
    marked[vert] = false; 
} 
  
// Counts cycles of length N in an undirected 
// and connected graph. 
int countCycles(bool graph[][V], int n) 
{ 
    // all vertex are marked un-visited initially. 
    bool marked[V]; 
    memset(marked, 0, sizeof(marked)); 
  
    // Searching for cycle by using v-n+1 vertices 
    int count = 0; 
    for (int i = 0; i < V - (n - 1); i++) { 
        DFS(graph, marked, n-1, i, i, count); 
  
        // ith vertex is marked as visited and 
        // will not be visited again. 
        marked[i] = true; 
    } 
  
    return count/2; 
} 
  
int main() 
{ 
    bool graph[][V] = {{0, 1, 0, 1, 0}, 
                      {1, 0, 1, 0, 1}, 
                      {0, 1, 0, 1, 0}, 
                      {1, 0, 1, 0, 1}, 
                      {0, 1, 0, 1, 0}}; 
    int n = 4; 
    cout << "Total cycles of length " << n << " are "
         << countCycles(graph, n); 
    return 0; 
}