what's this function mean ( sry for my english )

Question

what's this mean

int find(int u) { return P[u] = P[u] == u ? u : find(P[u]); }

full code(c++) -it tell which number are connected.

   #include <bits/stdc++.h>
using namespace std;

const int N = 1e5+5;

int n, m, k;
int P[N];

int find(int u) { return P[u] = P[u] == u ? u : find(P[u]); }

int main() {
    scanf("%d %d %d", &n, &m, &k);
    iota(P, P+N, 0);
    for(int i = 0, a, b; i < m; ++i) {
        scanf("%d %d", &a, &b);
        a = find(a), b = find(b);
        P[a] = b;
    }
    for(int i = 0, a, b; i < k; ++i) {
        scanf("%d %d", &a, &b);
        puts(find(a) == find(b) ? "yes" : "no");
    }
}

input- 3 2 3 1 2 2 1 2 3 3 1 1 2

out put- no no yes

**Recommended reading:** [Why should I not #include ?](https://stackoverflow.com/q/31816095/560648) — Asteroids With Wings, Jun 11 '20 at 16:36
Ask the person who wrote it to explain it, document it, and use meaningful variable names. We can only guess at what they intended; and, for what it's worth, I've tried and failed. — Asteroids With Wings, Jun 11 '20 at 16:40
Handy reading: [What does '?' do in C++?](https://stackoverflow.com/questions/795286/what-does-do-in-c) — user4581301, Jun 11 '20 at 16:41
This should be of use: https://stackoverflow.com/q/388242/2079303 — eerorika, Jun 11 '20 at 16:41
That code was not written to be read. It wouldn't survive code review at most companies, so don't expect to learn much from it. — user4581301, Jun 11 '20 at 16:42

Itati · Answer 1 · 2020-06-11T16:48:48.107

0

int find(int u) { return P[u] = P[u] == u ? u : find(P[u]); }

equal

int find(int u ) {
  if ( p[u] == u ) p[u] = u;
    else P[u] = find(P[u]);
  return P[u];
}

This is another way of writing

condition ? consequent : alternative

edited Jun 11 '20 at 16:48

answered Jun 11 '20 at 16:42

Itati

193
11

3

Right, but what does it _mean_? – Asteroids With Wings Jun 11 '20 at 16:43
What Atsteroids is trying to get you do do is explain the program behaviour the code is trying to express. What is that code doing? How does it solve the problem it's supposed to solve? What is the problem the code is supposed to solve? – user4581301 Jun 11 '20 at 17:05
@AsteroidsWithWings Oh, I misunderstood what he meant – Itati Jun 11 '20 at 17:17
@user4581301 Oh, I misunderstood what he meant. English is not my native language. – Itati Jun 11 '20 at 17:18
@Itati it's possible that all the questioner cares about is the syntax, but in general a discussion of syntax is of little use without discussing the behaviour the syntax is supposed to express. – user4581301 Jun 11 '20 at 17:41

what's this function mean ( sry for my english )

1 Answers1