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Dijkstra.cpp
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Dijkstra.cpp
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//author @Nishant
#include<bits/stdc++.h>
using namespace std;
int findMinVertex(int *dist, bool *visit, int n){
int minVertex = -1;
for(int i=0; i<n; i++){
if(!visit[i] && (minVertex == -1 || dist[i] < dist[minVertex])){
minVertex = i;
}
}
return minVertex;
}
void dijkstra(int **edges, int n){
int *dist = new int[n];
bool *visit = new bool[n];
int *pred = new int[n];
for(int i=0; i<n; i++){
dist[i] = 999;
visit[i] = false;
pred[i] = 0;
}
dist[0] = 0;
int next;
for(int i=0; i<n; i++){
int minVertex = findMinVertex(dist, visit, n);
visit[minVertex] = true;
for(int j=0; j<n; j++){
if(edges[minVertex][j] != 0 && !visit[j]){
int distance = dist[minVertex] + edges[minVertex][j];
if(distance < dist[j]){
dist[j] = distance;
next = i;
}
}
if(!visit[j]){
pred[j]=next;
}
}
}
int j;
for(int i=1; i<n; i++){
if(i != 0){
cout << "\nDistance of node" << i << "=" << dist[i];
cout << "\nPath=" << i;
j = i;
do{
j=pred[j];
cout << "<-" << j;
}while(j != 0);
}
}
}
int main(){
int N, wt;
cin >> N;
if(N>1){
int **edges = new int*[N];
for(int i=0; i<N; i++){
edges[i] = new int[N];
for(int j=0; j<N; j++){
edges[i][j] = 0;
}
}
for(int i=0; i<N; i++){
for(int j=0; j<N; j++){
cin >> wt;
if(wt!=0){
edges[i][j] = wt;
}else{
edges[i][j] = 0;
}
}
}
cin >> wt;
dijkstra(edges, N);
}
return 0;
}