104 lines
2.6 KiB
Java
104 lines
2.6 KiB
Java
import java.util.*;
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public class HolyKnightsTour {
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final static String[] board = {
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" xxx ",
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" x xx ",
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" xxxxxxx",
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"xxx x x",
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"x x xxx",
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"1xxxxxx ",
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" xx x ",
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" xxx "};
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private final static int base = 12;
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private final static int[][] moves = {{1, -2}, {2, -1}, {2, 1}, {1, 2},
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{-1, 2}, {-2, 1}, {-2, -1}, {-1, -2}};
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private static int[][] grid;
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private static int total = 2;
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public static void main(String[] args) {
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int row = 0, col = 0;
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grid = new int[base][base];
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for (int r = 0; r < base; r++) {
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Arrays.fill(grid[r], -1);
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for (int c = 2; c < base - 2; c++) {
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if (r >= 2 && r < base - 2) {
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if (board[r - 2].charAt(c - 2) == 'x') {
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grid[r][c] = 0;
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total++;
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}
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if (board[r - 2].charAt(c - 2) == '1') {
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row = r;
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col = c;
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}
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}
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}
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}
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grid[row][col] = 1;
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if (solve(row, col, 2))
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printResult();
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}
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private static boolean solve(int r, int c, int count) {
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if (count == total)
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return true;
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List<int[]> nbrs = neighbors(r, c);
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if (nbrs.isEmpty() && count != total)
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return false;
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Collections.sort(nbrs, (a, b) -> a[2] - b[2]);
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for (int[] nb : nbrs) {
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r = nb[0];
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c = nb[1];
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grid[r][c] = count;
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if (solve(r, c, count + 1))
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return true;
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grid[r][c] = 0;
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}
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return false;
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}
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private static List<int[]> neighbors(int r, int c) {
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List<int[]> nbrs = new ArrayList<>();
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for (int[] m : moves) {
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int x = m[0];
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int y = m[1];
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if (grid[r + y][c + x] == 0) {
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int num = countNeighbors(r + y, c + x) - 1;
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nbrs.add(new int[]{r + y, c + x, num});
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}
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}
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return nbrs;
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}
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private static int countNeighbors(int r, int c) {
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int num = 0;
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for (int[] m : moves)
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if (grid[r + m[1]][c + m[0]] == 0)
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num++;
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return num;
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}
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private static void printResult() {
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for (int[] row : grid) {
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for (int i : row) {
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if (i == -1)
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System.out.printf("%2s ", ' ');
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else
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System.out.printf("%2d ", i);
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}
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System.out.println();
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}
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}
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}
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