1 #include <stdio.h>
 2 #include <algorithm>
 3
 4 int A[3000];
 5 int n;
 6
 7 int main() {
 8     scanf("%d",&n);
 9     for (int i = 0; i < n; ++ i) {
10         scanf("%d",A + i);
11     }
12     std::sort(A,A + n);
13     int answer = 0;
14     for (int i = 1; i < n; ++ i) {
15         if (A[i] <= A[i - 1]) {
16             answer += A[i - 1] + 1 - A[i];
17             A[i] = A[i - 1] + 1;
18         }
19     }
20     printf("%d\n",answer);
21 }

 1 #include <bits/stdc++.h>
 2
 3 const int MOD = (int)1e9 + 7;
 4 const int N = 100000 + 5;
 5 std::vector<int> edges[N];
 6 int color[N];
 7 int n;
 8 int dp[N][2];
 9
10 inline void add(int &a,int b) {
11     a += b;
12     if (a >= MOD) a -= MOD;
13 }
14
15 void dfs(int u) {
16     if (color[u] == 1) {
17         dp[u][1] = 1;
18         dp[u][0] = 0;
19     } else {
20         dp[u][0] = 1;
21         dp[u][1] = 0;
22     }
23     for (int i = 0; i < edges[u].size(); ++ i) {
24         int v = edges[u][i];
25         dfs(v);
26         int tmp[2] = {};
27         for (int a = 0; a < 2; ++ a) {
28             for (int b = 0; b < 2; ++ b) {
29                 add(tmp[a | b],dp[u][a] * 1ll * dp[v][b] % MOD);
30                 if (a == 0 && b == 1) {
31                     add(tmp[0],dp[u][a] * 1ll * dp[v][b] % MOD);
32                 }
33             }
34         }
35         dp[u][0] = tmp[0];
36         dp[u][1] = tmp[1];
37     }
38
39 }
40
41 int work() {
42     dfs(0);
43     return dp[0][1];
44 }
45
46 int main() {
47     scanf("%d",&n);
48     for (int i = 1; i < n; ++ i) {
49         int x;
50         scanf("%d",&x);
51         edges[x].push_back(i);
52     }
53     for (int i = 0; i < n; ++ i) {
54         scanf("%d",color + i);
55     }
56     printf("%d\n",work());
57 }