1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
| class Solution {
int N = 510;
int[] cnts = new int[N], fa = new int[N];
boolean[][] g = new boolean[N][N];
public int checkWays(int[][] pairs) {
int m = pairs.length;
Set<Integer> set = new HashSet<>();
for (int[] p : pairs) {
int a = p[0], b = p[1];
g[a][b] = g[b][a] = true;
++cnts[a];
++cnts[b];
set.add(a);
set.add(b);
}
List<Integer> list = new ArrayList<>(set);
list.sort((a, b) -> cnts[b] - cnts[a]);
int n = list.size(), root = list.get(0);
if (m < n - 1) return 0;
fa[root] = -1;
for (int i = 1; i < n; i++) {
int a = list.get(i);
boolean flag = false;
for (int j = i - 1; j >= 0 && !flag; --j) {
int b = list.get(j);
if (g[a][b]) {
fa[a] = b;
flag = true;
}
}
if (!flag) return 0;
}
int c = 0, ans = 1;
for (int i : set) {
int j = i;
while (fa[j] != -1) {
if (!g[i][fa[j]]) return 0;
if (cnts[i] == cnts[fa[j]]) ans = 2;
++c;
j = fa[j];
}
}
return c < m ? 0 : ans;
}
}
|
wechat
