bfs but dfs

#include <bits/stdc++.h>
using namespace std;
int n;
vector<vector<int>>g(0);
vector<bool>used(0);
pair<int, string> dfs(int st, int nd){
    used[st] = true;
    if(st == nd){
        used[st] = false;
        return {0 , ""};
    }
    int c = g[st][nd];
    char x = char('A'+st);
    char y = char('A'+nd);
    char z = char('0' + g[st][nd]);
    string s = "";
    s+=y;
    s+=x;
    s+=z;
    for(int i = 0; i < n; i++){
        if(used[i])
            continue;
        auto par = dfs(i, nd);
        if( par.first + g[st][i] < c){
            c = par.first + g[st][i];
            s = par.second + "--" + char('A'+i) + x  + char('0' + g[st][i]);
        }

    }
    used[st] = false;
    return {c, s};
}

int main() {
    cin >> n;
    g.resize(n, vector<int>(n, 1000000));
    used.resize(n, false);
    for(int i = 0; i < n; i++){
        for(int j = 0; j < n; j++){
            int c;
            cin >> c;
            if(c > -1)
                g[i][j] = c;
        }
    }
    int a,b, c;
    cin >> a >> b >> c;
    auto par1 = dfs(b, a);
    auto par2 = dfs(c,b);
    cout << par1.first + par2.first << endl;
    cout << par1.second + "--" + par2.second << endl;

    return 0;
}