URAL1040 - Airline Company - dfs+思维

300人委员会的复仇

dfs and simiar

math

1.题意概述

gcd

YES

NO

2.解题思路

3.AC代码

struct Edge {
int to, val, next;
} E[maxn << 1];
int head
, vis
, cnt, gg, Gcd[maxn];
void init() {
memset(head, -1, sizeof head);
memset(vis, 0, sizeof vis);
memset(Gcd, 0, sizeof Gcd);
cnt = 0; gg = 1;
}
void addedge(int u, int v, int w) {
E[cnt].to = v;
E[cnt].val = w;
E[cnt].next = head[u];
head[u] = cnt++;
}
void dfs(int u) {
vis[u] = 1;
for (int i = head[u]; ~i; i = E[i].next) {
int v = E[i].to;
int id = E[i].val;
if (!Gcd[id]) {
Gcd[id] = gg++;
if (!vis[v]) dfs(v);
}
}
}
int main() {
int n, m;
init();
scanf("%d%d", &n, &m);
rep(i, 1, m + 1) {
int u, v;
scanf("%d%d", &u, &v);
addedge(u, v, i);
addedge(v, u, i);
}
bool flag = 1;
dfs(1);
//  rep(i, 1, m + 1) printf("%d ", Gcd[i]);
//  puts("");
rep(u, 1, n + 1) {
int g = 0, len = 0;
for (int i = head[u]; ~i; i = E[i].next) {
len++;
int id = E[i].val;
if (!g) g = Gcd[id];
else g = __gcd(g, Gcd[id]);
}
if (len > 1 && g != 1) {
flag = 0;
break;
}
}
if (flag) {
puts("YES");
rep(i, 1, m + 1)
if (i == m)
printf("%d\n", Gcd[i]);
else printf("%d ", Gcd[i]);
} else puts("NO");
return 0;
}