Graph Traversal

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

const int MAXN = 2e5 + 5;
vector<int> adj[MAXN];
bool vis[MAXN];
int dep[MAXN], par[MAXN], color[MAXN], deg[MAXN];
int n, m;

void dfs(int u, int p = -1, int d = 0) {
    vis[u] = true; par[u] = p; dep[u] = d;
    for (int v : adj[u])
        if (!vis[v]) dfs(v, u, d + 1);
}

int bfs(int src, int dest) {
    memset(vis, false, sizeof vis);
    memset(dep, 0x3f, sizeof dep);
    queue<int> q;
    q.push(src); vis[src] = true; dep[src] = 0;
    while (!q.empty()) {
        int u = q.front(); q.pop();
        for (int v : adj[u]) {
            if (!vis[v]) {
                vis[v] = true; par[v] = u;
                dep[v] = dep[u] + 1;
                q.push(v);
            }
        }
    }
    return dep[dest] >= 0x3f3f3f3f ? -1 : dep[dest];
}

bool isBipartite() {
    memset(color, 0, sizeof color);
    for (int i = 1; i <= n; i++) {
        if (color[i]) continue;
        queue<int> q;
        q.push(i); color[i] = 1;
        while (!q.empty()) {
            int u = q.front(); q.pop();
            for (int v : adj[u]) {
                if (!color[v]) { color[v] = -color[u]; q.push(v); }
                else if (color[v] == color[u]) return false;
            }
        }
    }
    return true;
}

bool hasCycle(int u, int p = -1) {
    vis[u] = true;
    for (int v : adj[u]) {
        if (!vis[v]) { if (hasCycle(v, u)) return true; }
        else if (v != p) return true;
    }
    return false;
}

vector<int> topoSort() {
    vector<int> order;
    int indeg[MAXN] = {};
    for (int u = 1; u <= n; u++)
        for (int v : adj[u]) indeg[v]++;
    queue<int> q;
    for (int i = 1; i <= n; i++)
        if (!indeg[i]) q.push(i);
    while (!q.empty()) {
        int u = q.front(); q.pop();
        order.push_back(u);
        for (int v : adj[u])
            if (--indeg[v] == 0) q.push(v);
    }
    return order;
}