### Andrew Stankevich’s Contest #9解题报告 » ZOJ2699

ZOJ2699.java

```import java.io.*;
import java.math.*;
import java.util.*;

public class Main {
private static int buffer = -1;

public static int nextInt() throws IOException {
int ret = 0;

do {
} while (Character.isWhitespace(buffer));
if (buffer == -1) {
return -1;
}
do {
ret *= 10;
ret += Character.digit(buffer, 10);
} while (Character.isDigit(buffer));

return ret;
}

static BigInteger[][] c;

static {
c = new BigInteger[101][101];
for (int i = 0; i < c.length; ++i) {
// Arrays.fill(c[i], BigInteger.ZERO);
c[i][0] = c[i][i] = BigInteger.ONE;
for (int j = 1; j < i; ++j) {
c[i][j] = c[i - 1][j - 1].add(c[i - 1][j]);
}
}
}

public static void main(String[] args) throws IOException {
while (true) {
int n = nextInt();
if (n < 0) {
break;
}
int m = nextInt();
int v = nextInt();
boolean[][] w = new boolean[n][n];
for (int i = 0; i < m; ++i) {
int a = nextInt();
int b = nextInt();
w[a - 1][b - 1] = true;
}
// floyd
for (int k = 0; k < n; ++k) {
for (int i = 0; i < n; ++i) {
for (int j = 0; j < n; ++j) {
w[i][j] |= w[i][k] && w[k][j];
}
}
}

int[] id = new int[n], sz = new int[n];
ArrayList<Integer> x = new ArrayList<Integer>();
int y = 0;
// relabel
for (int i = 0; i < n; ++i) {
id[i] = i;
for (int j = 0; j < i; ++j) {
if (w[i][j] && w[j][i]) {
id[i] = id[j];
break;
}
}
++sz[id[i]];
}
//
for (int i = 0; i < n; ++i) {
boolean hasIn = false, hasOut = false;
if (id[i] < i) {
continue;
}
for (int j = 0; j < n; ++j) {
if (id[i] != id[j]) {
if (w[i][j]) {
hasOut = true;
}
if (w[j][i]) {
hasIn = true;
}
}
}
if (hasIn && hasOut) {
y += sz[id[i]];
} else {
}
}

// dp
BigInteger[] dp = new BigInteger[v + 1];
Arrays.fill(dp, BigInteger.ZERO);
dp[0] = BigInteger.ONE;
for (int xi : x) {
BigInteger[] pd = new BigInteger[v + 1];
Arrays.fill(pd, BigInteger.ZERO);
for (int j = 1; j <= xi; ++j) {
for (int k = j; k <= v; ++k) {
}
}
dp = pd;
}

BigInteger ans = BigInteger.ZERO;
for (int j = 0; j <= y && j <= v; ++j) {