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Dijkstra
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Dijkstra
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#include<cstdio>
#include<iostream>
#define sf scanf
#define pf printf
#define inf 999
#define nil -1
#define white 0
#define black 3
using namespace std;
int node,edge,W[100][100],cost[100],par[100],state[100];
void relax(int u, int v, int w)
{
if(cost[v]>cost[u]+w)
{
cost[v] = cost[u]+w;
par[v] = u;
}
}
void initialize_single_source(int s)
{
for(int i=1;i<=node;i++)
{
cost[i] = inf;
par[i] = nil;
state[i] = white;
}
cost[s] = 0;
}
int extract_min()
{
int min_cost = inf;
int min_ver = 0;
for(int i=1;i<=node;i++)
{
if(state[i] == white and cost[i]<min_cost)
{
min_cost = cost[i];
min_ver=i;
}
}
return min_ver;
}
void Dijkstra(int s)
{
int u;
initialize_single_source(s);
for(int i=1;i<=node;i++)
{
u = extract_min();
state[u] = black;
for(int j=1;j<=node;j++)
{
if(state[j]==white and W[i][j]!=inf)
{
relax(u,j,W[u][j]);
}
}
}
}
void path(int s, int v)
{
if(v == s)
{
pf("%d ",s);
}
else if(par[v] == nil)
{
pf("no path..");
}
else
{
path(s,par[v]);
pf("%d ",v);
}
}
int main()
{
pf("Enter node and edge: ");
sf("%d %d",&node,&edge);
for(int i=0;i<=node;i++)
{
for(int j=0;j<=node;j++)
{
W[i][j] = inf;
}
}
for(int i=1;i<=edge;i++)
{
int x,y,cost;
sf("%d %d %d",&x,&y,&cost);
W[x][y] = cost;
}
pf("Weight Matrix:\n");
for(int i=1;i<=node;i++)
{
for(int j=1;j<=node;j++)
{
pf("%d ",W[i][j]);
}
pf("\n");
}
int src;
pf("Enter start node: ");
sf("%d",&src);
Dijkstra(src);
pf("parent array:\n");
for(int i=1;i<=node;i++)pf("%d ",par[i]);
int en;
pf("Enter end node: ");
sf("%d",&en);
pf("path: ");
path(src,en);
}