PetersonGraph.cpp

#include <bits/stdc++.h> 
using namespace std; 

char S[100005]; 

bool adj[10][10]; 

char result[100005]; 

bool findthepath(char* S, int v) 
{ 
	result[0] = v + '0'; 
	for (int i = 1; S[i]; i++) { 
		
		if (adj[v][S[i] - 'A'] || adj[S[i] - 
							'A'][v]) { 
			v = S[i] - 'A'; 
		} 

		else if (adj[v][S[i] - 'A' + 5] || 
				adj[S[i] - 'A' + 5][v]) { 
			v = S[i] - 'A' + 5; 
		} 

		else
			return false; 

		result[i] = v + '0'; 
	} 

	return true; 
} 

int main() 
{ 
	adj[0][1] = adj[1][2] = adj[2][3] = 
    adj[3][4] = adj[4][0] = adj[0][5] = 
    adj[1][6] = adj[2][7] = adj[3][8] = 
    adj[4][9] = adj[5][7] = adj[7][9] = 
	adj[9][6] = adj[6][8] = adj[8][5] = true; 
	
	char S[] = "ABB"; 
	
	if (findthepath(S, S[0] - 'A') || 
		findthepath(S, S[0] - 'A' + 5)) { 
		cout << result; 
	}
     
    else { 
		cout << "-1"; 
	} 
	return 0; 
}