Distance from Source Graph

Author: eatsleepcoderepeat9

dist_from_source.cpp

@@ -0,0 +1,62 @@
+//https://www.codechef.com/problems/BUG2K17B
+#include<bits/stdc++.h>
+#define mp pair<int,int>
+using namespace std;
+
+int debugg=0;
+class Node{
+    public:
+    int dist;
+    vector<pair<int,int> > next;//first contains city index .. second contains distance
+    
+    void clear(){
+        dist=INT_MAX;
+        next.clear();
+    }
+} node[100002];
+
+struct priority_fxn{
+    bool operator() (int a,int b){
+       return node[a].dist > node[b].dist; 
+    }
+};
+void dijakstra(int source){
+    int n,d,temp;
+    priority_queue<int,vector<int>,priority_fxn> q;
+    
+    //init queue
+    node[source].dist=0;
+    q.push(source);
+    
+    while(!q.empty()){
+        temp=q.top();
+        for(auto elem : node[temp].next){
+            n=elem.first;
+            d=elem.second;
+            if(node[n].dist > node[temp].dist + d){
+                node[n].dist = node[temp].dist + d;
+                q.push(n);
+            }    
+        }
+        q.pop();
+    }
+}
+
+int main(){
+    int t,a,b,c,n,p;
+    cin>>t;
+    while(t--){
+        cin>>n>>p;
+        for(int i=1;i<=n;i++)
+            node[i].clear();
+        while(p--){
+            cin>>a>>b>>c;
+            node[a].next.push_back(mp(b,c));
+            node[b].next.push_back(mp(a,c));
+        }
+        dijakstra(1);
+        if(node[n].dist==INT_MAX)cout<<"NONE"<<endl;
+        else
+            cout<<node[n].dist<<endl;
+    }
+}