69 lines
1.8 KiB
Plaintext
69 lines
1.8 KiB
Plaintext
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const int maxn = 18;
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const int mod = 1000000007;
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int dp[maxn][maxn][maxn][maxn][maxn][7];
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int list[200];
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int equal(int a, int b) {
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if (a == b)
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return 1;
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return 0;
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}
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int dfs(int a, int b, int c, int d, int e, int last){
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if(dp[a][b][c][d][e][last] != -1)
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return dp[a][b][c][d][e][last];
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if(a + b + c + d + e == 0)
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return 1;
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int ans = 0;
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if (a) ans = (ans + (a - equal(last, 2)) * dfs(a - 1, b, c, d, e, 1)) % mod;
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if (b) ans = (ans + (b - equal(last, 3)) * dfs(a + 1, b - 1, c, d, e, 2)) % mod;
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if (c) ans = (ans + (c - equal(last, 4)) * dfs(a, b + 1, c - 1, d, e, 3)) % mod;
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if (d) ans = (ans + (d - equal(last, 5)) * dfs(a, b, c + 1, d - 1, e, 4)) % mod;
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if (e) ans = (ans + e * dfs(a, b, c, d + 1, e - 1, 5)) % mod;
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dp[a][b][c][d][e][last] = ans % mod;
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return dp[a][b][c][d][e][last];
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}
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int cns[20];
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int main(){
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int n = getint();
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int i = 0;
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while (i < maxn) {
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int j = 0;
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while(j < maxn) {
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int k = 0;
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while(k < maxn) {
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int l = 0;
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while (l < maxn) {
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int m = 0;
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while (m < maxn) {
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int h = 0;
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while (h < 7) {
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dp[i][j][k][l][m][h] = -1;
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h = h + 1;
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}
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m = m + 1;
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}
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l = l + 1;
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}
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k = k + 1;
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}
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j = j + 1;
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}
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i = i + 1;
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}
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i = 0;
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while (i < n) {
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list[i] = getint();
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cns[list[i]] = cns[list[i]] + 1;
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i = i + 1;
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}
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int ans = dfs(cns[1], cns[2], cns[3], cns[4], cns[5], 0);
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putint(ans);
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return ans;
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}
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