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Copy pathGraphPathsII.java
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143 lines (123 loc) · 3.91 KB
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package cses.math;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Arrays;
import java.util.Random;
import java.util.StringTokenizer;
public final class GraphPathsII {
// https://cp-algorithms.com/graph/fixed_length_paths.html
public static void main(String[] args) {
final FastScanner fs = new FastScanner();
final int n = fs.nextInt();
final int m = fs.nextInt();
final int k = fs.nextInt();
long[][] mat = new long[n][n];
for (long[] row : mat) {
Arrays.fill(row, (long) 4e18);
}
for (int i = 0; i < m; i++) {
final int u = fs.nextInt() - 1;
final int v = fs.nextInt() - 1;
final int c = fs.nextInt();
mat[u][v] = Math.min(mat[u][v], c);
}
mat = pow(mat, k);
final long res = mat[0][n - 1];
System.out.println(res == (long) 4e18 ? -1 : res);
}
private static long[][] pow(long[][] m, long k) {
if (k == 1) {
return m;
}
long[][] u = pow(m, k / 2);
u = min(u, u);
if (k % 2 != 0) {
u = min(u, m);
}
return u;
}
private static long[][] min(long[][] left, long[][] right) {
final int lRow = left.length;
final int lCol = left[0].length;
final int rCol = right[0].length;
final long[][] res = new long[lRow][rCol];
for (long[] row : res) {
Arrays.fill(row, (long) 4e18);
}
for (int i = 0; i < lRow; i++) {
for (int k = 0; k < lCol; k++) {
for (int j = 0; j < rCol; j++) {
res[i][j] = Math.min(res[i][j], left[i][k] + right[k][j]);
}
}
}
return res;
}
static final class Utils {
public static void shuffleSort(int[] x) {
shuffle(x);
Arrays.sort(x);
}
public static void shuffleSort(long[] x) {
shuffle(x);
Arrays.sort(x);
}
public static void shuffle(int[] x) {
final Random r = new Random();
for (int i = 0; i <= x.length - 2; i++) {
final int j = i + r.nextInt(x.length - i);
swap(x, i, j);
}
}
public static void shuffle(long[] x) {
final Random r = new Random();
for (int i = 0; i <= x.length - 2; i++) {
final int j = i + r.nextInt(x.length - i);
swap(x, i, j);
}
}
public static void swap(int[] x, int i, int j) {
final int t = x[i];
x[i] = x[j];
x[j] = t;
}
public static void swap(long[] x, int i, int j) {
final long t = x[i];
x[i] = x[j];
x[j] = t;
}
private Utils() {}
}
static class FastScanner {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
StringTokenizer st = new StringTokenizer("");
private String next() {
while (!st.hasMoreTokens()) {
try {
st = new StringTokenizer(br.readLine());
} catch (IOException e) {
//noinspection CallToPrintStackTrace
e.printStackTrace();
}
}
return st.nextToken();
}
int nextInt() {
return Integer.parseInt(next());
}
long nextLong() {
return Long.parseLong(next());
}
int[] nextIntArray(int n) {
final int[] a = new int[n];
for (int i = 0; i < n; i++) { a[i] = nextInt(); }
return a;
}
long[] nextLongArray(int n) {
final long[] a = new long[n];
for (int i = 0; i < n; i++) { a[i] = nextLong(); }
return a;
}
}
}