Cycle Detection

#include <cstring>
#define push_back pb
#include <vector>
#include <iostream>
using namespace std;

int cycle = -1;
vector<int> g[100005];

bool visited[100005];

void dfs(int v, int parent = -1) {
    visited[v] = 1;
    for (int i=0; i < g[v].size(); i++) {
        if (g[v][i] == parent) {
            continue;
        }

        else if (visited[g[v][i]] == 0) {
            dfs(g[v][i], v);
        }

        else if (visited[g[v][i]] == 1) {
            cycle = 1;
        }
    }

    visited[v] = 2;
}

int tot = 0;

int main() {
    int x;
    cin >> x;
    int tot = 0;
    for (int i=0; i < x; i++) {
        for (int j=0; j < x; j++) {
            int z;
            cin >> z;
            if (z==1) {
                tot += 1;
                g[i].pb(j);
                g[j].pb(i);
            }
        }
    }

    dfs(0);
    int vis = 0;
    for (int i=0; i < 1000; i++) {
        if (visited[i]) { vis += 1; }
    }

    for (int i=0; i < x; i++) {
        memset(visited, 0, sizeof(visited));
        dfs(i);
    }

    if (cycle == 1) {
        cout << 123 << endl;
    }

    if (tot == 2*(x-1) && vis == x) {
        cout << "YES" << endl;
    }

    else {
        cout << "NO" << endl;
    }
    return 0;
}