Check if a graph is bipartite using DFS bicoloring

is_bipartite.cpp

#include <bits/stdc++.h>

using namespace std;
typedef long long ll;

bool is_bipartite(unordered_map<ll, vector<ll>> &graph, vector<ll> &color, ll curNode = 1, ll curColor = 1) {
    if(color[curNode]) return true;
    color[curNode] = curColor;
    bool ans = true;
    for(ll i : graph[curNode]){
        if(color[curNode] == color[i]) return false;
        ans = min(ans, is_bipartite(graph, color, i, -curColor));
    }
    return ans;
}

int main() {
    ll nodeNum, edgeNum;
    cin >> nodeNum >> edgeNum;
    unordered_map<ll, vector<ll>> graph;
    for (ll i = 0; i < edgeNum; i++) {
        ll a, b;
        cin >> a >> b;
        graph[a].push_back(b);
        graph[b].push_back(a);
    }
    vector<ll> color(nodeNum + 1);
    cout << is_bipartite(graph, color);
}