From 6922d2fa3928f8d3488a4421c00bda6a07d32026 Mon Sep 17 00:00:00 2001
From: Siddharth6780 <63189333+Siddharth6780@users.noreply.github.com>
Date: Fri, 2 Oct 2020 00:01:53 +0530
Subject: [PATCH] Create Cycle_Detection.cpp

---
 Cycle_Detection.cpp | 57 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 57 insertions(+)
 create mode 100644 Cycle_Detection.cpp

diff --git a/Cycle_Detection.cpp b/Cycle_Detection.cpp
new file mode 100644
index 0000000..5385e83
--- /dev/null
+++ b/Cycle_Detection.cpp
@@ -0,0 +1,57 @@
+#include<bits/stdc++.h>
+using namespace std;
+#define ll  long long
+#define fio ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL)
+#define endl '\n'
+#define mod 1000000007
+bool Cycle_Detection_helper(map<int, vector<int>>m, bool *visited, int src, int parent) {
+    visited[src] = true;
+    for (auto nbr : m[src]) {
+        if (visited[nbr] == false) {
+            bool cycle_found = Cycle_Detection_helper(m, visited, nbr, src);
+            if (cycle_found) {
+                return true;
+            }
+        }
+        else if (nbr != parent) {
+            return true;
+        }
+    }
+
+    return false;
+}
+bool Cycle_Detection(map<int, vector<int>>m, int n) {
+    bool visited[n];
+    for (int i = 0; i < n; i++) {
+        visited[i] = false;
+    }
+    int src;
+    cin >> src;
+    return Cycle_Detection_helper(m, visited, src, -1);
+}
+int main() {
+    fio;
+    int n;
+    cin >> n;
+    map<int, vector<int>>m;
+    for (int i = 0; i < n; i++) {
+        int x, y;
+        cin >> x >> y;
+        m[x].push_back(y);
+        m[y].push_back(x);
+    }
+    if (Cycle_Detection(m, n)) {
+        cout << "Yes" << endl;
+    }
+    else {
+        cout << "No" << endl;
+    }
+    for (auto p : m) {
+        cout << p.first << "-->";
+        for (auto p1 : p.second) {
+            cout << p1 << " ";
+        }
+        cout << endl;
+    }
+    return 0;
+}