While reading about Finding Bridges in a Graph I came across an article Article link on a website. I was amazed that void dfs(int v, int p = -1) {.....} In the code there were two types of function call 1) dfs(to, v); 2) dfs(i); I thought this might give a wrong answer but both of them were working. When nothing was passed the value of p was -1 and when a value was passed p took that value.

#include <iostream>
using namespace std;
void dfs(int p=-1)
{
	printf("%d",p);
}

int main() {
	int a=5;
	dfs(a);
	return 0;
}

Output: 5 Now the second case.

#include <iostream>
using namespace std;
void dfs(int p=-1)
{
	printf("%d",p);
}
int main() {
	
	dfs();
	return 0;
}

Output:-1 Amazed!! So this feature can be used when like starting of recursive calls when there is no parent for the source but after that, each node has a parent.

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