So I was golfing this problem, and I wanted to improve the line int c = t[v] = 1;, so I tried c = t[v] = 1;, with c defined earlier on in the same spot as a and b, but this didn't work. For the sample case, it gave the output 1 1 1 0 0 instead of 1 0 0 1 1.

I was wondering what that line actually does and if I can golf it more, so I found this question on quora, but even after reading that I still don't know why the other way isn't working. I use VSCode, so when I hover over the t[v] part, it says something to do with a reference to part of the bitset, so I'm thinking it's almost like a pointer to that index of the bitset, but that doesn't make sense because we're incrementing it, and you can't really increment a boolean value (which is basically what t[v] is..

#include <bits/stdc++.h>
using namespace std;
using I = int;
set<I> g[7<<14];
I n, m, a, b;
bitset<7<<14> s, t;

I d(I v) {
	I c = t[v] = 1;
	for (I u: g[v])
		t[u] ? c : c += d(u);
	return c;
}

main(){
	cin >> n >> m;
	while (m--)
		cin >> a >> b,
		g[a].insert(b),
		g[b].insert(a);
	for (a = s[0] = 1; a <= n; ++a)
		t[a] ? s : s |= s << d(a);
	for (a = 1; a <= n; )
		cout << s[a++];
}