Below code is for Bellman Ford algorithm and it gives wrong output when I use const int INF=INT_MAX
but correct output when I use const int INF=1e9
in line number 3.
Any idea why?
Code:
#include"bits/stdc++.h"
using namespace std;
const int INF=1e9;
int main()
{
int n,m;
cin>>n>>m;
vector<vector<int>> edges;
for(int i=0;i<m;i++)
{
int u,v,w;
cin>>u>>v>>w;
edges.push_back({u,v,w});
}
int src;
cin>>src;
vector<int> dist(n,INF);
dist[src]=0;
for(int iter=0;iter<n-1;iter++)
{
for(auto e:edges)
{
int u=e[0];
int v=e[1];
int w=e[2];
dist[v]=min(dist[v],w+dist[u]);
}
}
for(auto i:dist)
{
cout<<i<<" ";
}
}
Sample Input:
5 8
1 2 3
3 2 5
1 3 2
3 1 1
1 4 2
0 2 4
4 3 -3
0 1 -1
0
Expected Output: 0 -1 2 -2 1
Signed integer overflow here w+dist[u]
. The simple fix:
dist[v] = static_cast<int>(min(static_cast<long long>(dist[v]), static_cast<long long>(w) + dist[u]));