Create 1334. Find the City With the Smallest Number of Neighbors at a Threshold Distance.cpp

Author: wargraver

Leetcode/Gaph/1334. Find the City With the Smallest Number of Neighbors at a Threshold Distance.cpp

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+//Creating a set of key(distance,index) for looking up minimum distance in logn time
+set<pair<int,int>> pq;
+//Global Matrix for storing weight of each edge
+int wt[105][105];
+
+class Solution {
+public:
+    void djkstrA(int i,int dp[],int n,vector<int> adj[]){
+        if(pq.size()==0) return;
+        else{
+            auto kt = pq.begin();
+            int dist = kt->first;
+            int ind = kt->second;
+            pq.erase(kt);
+            for(auto x:adj[ind]){
+                if(dp[x]>dp[ind]+wt[ind][x]){
+                    auto it = pq.find({dp[x],x});
+                    pq.erase(it);
+                    dp[x] = dp[ind]+wt[ind][x];
+                    pq.insert({dp[x],x});
+                }
+            }
+            djkstrA(i,dp,n,adj);
+        }
+    }
+    int findTheCity(int n, vector<vector<int>>& edges, int d) {
+        int i,j,k,m,ct=0,val,ans=1e9;
+        vector<int> adj[n];
+        for(i=0;i<edges.size();i++){
+            j = edges[i][0];
+            k = edges[i][1];
+            wt[k][j] = edges[i][2];
+            wt[j][k] = edges[i][2];
+            adj[j].push_back(k);
+            adj[k].push_back(j);
+        }
+        //Checking for every node and using DjkstrA for each and every node as source
+        for(i=0;i<n;i++){
+            int dp[n];
+            pq.clear();
+            for(j=0;j<n;j++) dp[j]=1e9;
+            dp[i]=0;
+            for(j=0;j<n;j++) pq.insert({dp[j],j});
+            djkstrA(i,dp,n,adj);
+            int k=0;
+            for(j=0;j<n;j++){
+                if(dp[j]<=d) k++;
+            }
+            if(ans>=k){
+                ans=k;
+                val=i;
+            }
+        }
+        return val;
+    }
+};