Java每日一练(20230421) 整数排列、数组排序、单词搜索

import java.util.*;
public class Solution {
   public static void main(String[] args) {
      String str[] = { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9" };
      permutation(str, 0, str.length);
   }
   static void swap(String[] str, int start, int end) {
      String tmep = str[start];
      str[start] = str[end];
      str[end] = tmep;
   }
   static void permutation(String[] str, int start, int end) {
      if (start == end - 1) {
         for (int i = 0; i < end; i++) {
            System.out.print(str[i]);
         }
         System.out.println();
      } else {
         for (int i = start; i < end; i++) {
            if (i == 0 && str[0].equals("0"))
               continue;
            swap(str, start, i);
            permutation(str, start + 1, end);
            swap(str, start, i);
         }
      }
   }
}

class demo_sort {
    public static void main(String[] args) {
        int[] numbers = new int[] { 1, 5, 8, 2, 3, 9, 4 };
        for (int i = 0; i < numbers.length - 1; i++) {
            for (int j = 0; j < numbers.length - 1 - i; j++) {
                if (numbers[j] > numbers[j + 1]) {
                    int temp = numbers[j];
                    numbers[j] = numbers[j + 1];
                    numbers[j + 1] = temp;
                }
            }
        }
        System.out.println("从小到大排序后的结果是:");
        for (int i = 0; i < numbers.length; i++)
            System.out.print(numbers[i] + " ");
    }
}

import java.util.*;
class exist {
    public static class Solution {
        public boolean exist(char[][] board, String word) {
            int cl = board.length;
            int rl = board[0].length;
            boolean[][] flag = new boolean[cl][rl];
            for (int i = 0; i < cl; i++) {
                for (int j = 0; j < rl; j++) {
                    if (find(board, word, flag, i, j, 0))
                        return true;
                }
            }
            return false;
        }
        public boolean find(char[][] board, String word, boolean[][] flag, int i, int j, int index) {
            int cl = board.length;
            int rl = board[0].length;
            if (word.length() == index)
                return true;
            if (i < 0 || i >= cl || j >= rl || j < 0)
                return false;
            if (flag[i][j] || word.charAt(index) != board[i][j])
                return false;
            flag[i][j] = true;
            boolean judge = find(board, word, flag, i - 1, j, index + 1) || find(board, word, flag, i + 1, j, index + 1) || find(board, word, flag, i, j - 1, index + 1) || find(board, word, flag, i, j + 1, index + 1);
            flag[i][j] = false;
            return judge;
        }
    }
    public static void main(String[] args) {
        Solution s = new Solution();
        char[][] board = {{'A','B','C','E'},{'S','F','C','S'},{'A','D','E','E'}};
        String word = "ABCCED";
        System.out.println(s.exist(board, word));
        word = "SEE";
        System.out.println(s.exist(board, word));
        word = "ABCB";
        System.out.println(s.exist(board, word));
   }
}