Coloring

input/code.cpp: In function 'void color_vertex(int)':
input/code.cpp:12:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int j = 0; j < graph[i].size(); ++j) {
                                    ^
input/code.cpp:22:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int j = 0; j < graph[i].size(); ++j) {
                                    ^
input/code.cpp:25:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int j = 0; j < graph[i].size(); ++j) {
                                    ^

#include <iostream>
#include <vector>

const int N = 5 * (1e5);
int color [N+1];
bool legal [N+1];
std::vector<int> graph [N];
int max = 0;

void color_vertex(int i) {
	if (color[i]) return;
	for (int j = 0; j < graph[i].size(); ++j) {
		legal[color[graph[i][j]]] = false;
	}
	for (int j = 1;; ++j) {
		if (legal[j]) {
			color[i] = j;
			if (j > max) max = j;
			break;
		}
	}
	for (int j = 0; j < graph[i].size(); ++j) {
		legal[color[graph[i][j]]] = true;
	}
	for (int j = 0; j < graph[i].size(); ++j) {
		color_vertex(graph[i][j]);
	}
}

int main() {
	std::ios_base::sync_with_stdio(false);
	std::cin.tie(0);

	int n, m;
	std::cin >> n >> m;
	for (int i = 1; i <= n; ++i) legal[i] = true;

	for (int i = 0; i < m; ++i) {
		int a, b;
		std::cin >> a >> b;
		--a; --b;
		graph[a].push_back(b);
		graph[b].push_back(a);
	}
	color_vertex(0);
	std::cout << max << '\n';
	for (int i = 0; i < n; ++i) {
		std::cout << color[i] << ' ';
	}
	std::cout << '\n';
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: WRONG ANSWER

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: WRONG ANSWER

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: WRONG ANSWER

Test 12

Verdict: WRONG ANSWER

Test 13

Verdict: WRONG ANSWER

Test 14

Verdict: WRONG ANSWER

Test 15

Verdict: WRONG ANSWER

Test 16

Verdict: WRONG ANSWER

Test 17

Verdict: WRONG ANSWER

Test 18

Verdict: WRONG ANSWER

Test 19

Verdict: WRONG ANSWER

Test 20

Verdict: WRONG ANSWER

Test 21

Verdict: WRONG ANSWER

Test 22

Verdict: WRONG ANSWER

Test 23

Verdict: WRONG ANSWER

Test 24

Verdict: WRONG ANSWER

Test 25

Verdict: WRONG ANSWER

Test 26

Verdict: WRONG ANSWER

Test 27

Verdict: WRONG ANSWER

Test 28

Verdict: WRONG ANSWER

Test 29

Verdict: WRONG ANSWER

Test 30

Verdict: WRONG ANSWER

Test 31

Verdict: WRONG ANSWER

Test 32

Verdict: WRONG ANSWER

Test 33

Verdict: WRONG ANSWER

Test 34

Verdict: WRONG ANSWER

Test 35

Verdict: WRONG ANSWER

Test 36

Verdict: WRONG ANSWER

Test 37

Verdict: WRONG ANSWER

Test 38

Verdict: ACCEPTED

Test 39

Verdict: WRONG ANSWER

Test 40

Verdict: WRONG ANSWER

Test 41

Verdict: WRONG ANSWER

Test 42

Verdict: WRONG ANSWER

Test 43

Verdict: WRONG ANSWER

Test 44

Verdict: WRONG ANSWER

Test 45

Verdict: WRONG ANSWER

Test 46

Verdict: WRONG ANSWER

Test 47

Verdict: WRONG ANSWER

Test 48

Verdict: ACCEPTED

Test 49

Verdict: WRONG ANSWER

Test 50

Verdict: WRONG ANSWER