From 3590c0c4af96c347b6b32f5f281d193d331b1c8a Mon Sep 17 00:00:00 2001
From: shubhankk7 <56992145+shubhankk7@users.noreply.github.com>
Date: Fri, 25 Oct 2019 11:46:49 +0530
Subject: [PATCH] Create PT07Y.cpp

---
 PT07Y.cpp | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)
 create mode 100644 PT07Y.cpp

diff --git a/PT07Y.cpp b/PT07Y.cpp
new file mode 100644
index 0000000..461ddb5
--- /dev/null
+++ b/PT07Y.cpp
@@ -0,0 +1,54 @@
+#include<bits/stdc++.h>
+using namespace std;
+vector<long int>graph[10000];
+long int n,m,i,j;
+bool iscycle(long int s,bool visited[],long int parent)
+{
+    visited[s]=true;
+    vector<long int>::iterator it;
+    for(it=graph[s].begin();it!=graph[s].end();it++)
+    {
+        if(visited[*it]==false)
+        {
+            if(iscycle(*it,visited,s))
+                return true;
+        }
+         else if(*it!=parent)
+                return true;
+    }
+    return false;
+}
+bool istree(long int s)
+{
+    bool visited[n];
+    memset(visited,false,sizeof(visited));
+    //cout<<"here";
+    if(iscycle(i,visited,-1))
+       return false;
+    for(long int i=0;i<n;i++)
+        if(visited[i]==false)
+           return false;
+    return true;
+}
+void addedge(long int i,long int j)
+{
+    graph[i].push_back(j);
+    graph[j].push_back(i);
+}
+int main()
+{
+    cin>>n>>m;
+    //long int i,j;
+    while(m--)
+    {
+        cin>>i>>j;
+        i--,j--;
+        addedge(i,j);
+    }
+    //cout<<i;
+    if(istree(i))
+    {
+     cout<<"YES";
+    }
+    else cout<<"NO";
+}