Sudoku Solver在Java中使用回溯方法

Question

我正在尝试在java中创建一个Sudoku解算器，但它没有按预期工作，我无法弄清楚为什么。我在评论中添加了以下代码，所以希望有人可以找出问题所在。由于某种原因，它在中间停止。我怀疑它是一个无限循环，没有错误，但我无法识别它。有更多的代码，但它没有必要，因为它只是打印板和填充板。

private static int row2 = 0;
private static int col2 = 0;
private static boolean isEnd = false;

public static void backTrack(String[][] puzzle) { 
    int[][] puzzle2 = new int[9][9];
    for (int i = 0; i < 9; i++) {
        for (int i2 = 0; i2 < 9; i2++) {
            puzzle2[i][i2] = Integer.parseInt(puzzle[i][i2]); //Takes the String puzzle and turns it into integers and adds it to puzzle2
        }
    }
    int[][] puzzle3 = new int[9][9];
    puzzle3 = puzzle2; //Initiates puzzle3 so that I can have a fresh copy that I can use to reference to later
    while (isEnd == false) { //isEnd is defined in nextCell and determines whether or not the solution has been found or not
        if (puzzle3[row2][col2] != 0) {
            nextCell(); //if the cell was originally already set (that is why I use puzzle3), then it should just go to the next cell
        } else if (puzzle3[row2][col2] == 0) { //0 being empty. So if the cell was not originally filled
            while (puzzle2[row2][col2] <= 9) {
                puzzle2[row2][col2] = puzzle2[row2][col2] + 1; //Add 1 to the current number in the cell
                if (puzzle2[row2][col2] == 10) { //If it is 10, since it can, then it means that none of the numbers have worked in that cell, so it should go back a cell
                    puzzle2[row2][col2] = 0;//Sets it to 0 before going back one cell
                    backCell(); //method to go back a cell
                    while(true){
                        if(puzzle3[row2][col2]!=0){
                            backCell(); //if the cell it goes back onto was originally set, then it should keep going back until it finds one that it can change
                        }
                        else{
                            break; //breaks out of the infinite while loop , so that it can carry on checking solutions from the cell it just went onto. 
                        }
                    }
                    break; //breaks out of the second while loop
                }
                if (isValid(row2, col2, puzzle2[row2][col2], puzzle2)) {
                    nextCell(); //if the new number is valid, then it should go to the next cell and try out solutions from there
                    break;
                }
            }
        }
    }

    printBoard2(puzzle2); // method to print the board(which is meant to be solved at this point
}
public static void backCell() {
    col2--; 
    if (col2 < 0) { 
        col2 = 8;
        row2--;
    }
    if (row2 < 0) {
        row2 = 0;
        col2 = 0;
    }
}

public static void nextCell() {
    col2++;
    if (col2 > 8) {
        col2 = 0;
        row2++;
    }
    if (row2 > 8) {
        isEnd = true; //if it manages to reach the end of the puzzle, it can be assumed that the solution has been found
    }
}
 public static boolean isValid(int row, int col, int value, int[][]puzzle) {     
    boolean check = true;
    for (int i3 = 0; i3 < 9; i3++) {
        if (i3 != col) {
            if (puzzle[row][i3] == (value)) {
                check = false;
                break;

            }//checks whether the values are repeated in the same row
        }

    }
    for (int i3 = 0; i3 < 9; i3++) {
        if (i3 != row) {
            if (puzzle[i3][col] == (value)) {
                check = false;
                break;
            }
        }//checks whether the values are repeated in the same column

    }

    int initRow = 0;
    int initCol = 0;
    if (row <= 2) {
        initRow = 0;
    } else if (row <= 5 && row > 2) {
        initRow = 3;
    } else if (row <= 8 && row > 5) {
        initRow = 6;
    }
    if (col <= 2) {
        initCol = 0;
    } else if (col <= 5 && col > 2) {
        initCol = 3;
    } else if (col <= 8 && col > 5) {
        initCol = 6;
    }//finds the top left coordinates of the box that it is in

    if (puzzle[initRow][initCol] == value
            && (initRow != row || initCol != col)) {
        check = false; //checks whether the value is in the box. The second part of each if statement checks whether the coordinates are the same as the value entered(since the value is already added before validation)
    }
    if (puzzle[initRow + 1][initCol] == value
            && ((initRow + 1) != row || initCol != col)) {
        check = false;
    }
    if (puzzle[initRow + 2][initCol] == value
            && ((initRow + 2) != row || initCol != col)) {
        check = false;
    }
    if (puzzle[initRow][initCol + 1] == value
            && (initRow != row || (initCol + 1) != col)) {
        check = false;
    }
    if (puzzle[initRow][initCol + 2] == value
            && (initRow != row || (initCol + 2) != col)) {
        check = false;
    }
    if (puzzle[initRow + 1][initCol + 1] == value
            && ((initRow + 1) != row || (initCol + 1) != col)) {
        check = false;
    }
    if (puzzle[initRow + 2][initCol + 1] == value
            && ((initRow + 2) != row || (initCol + 1) != col)) {
        check = false;
    }
    if (puzzle[initRow + 1][initCol + 2] == value
            && ((initRow + 1) != row || (initCol + 2) != col)) {
        check = false;
    }
    if (puzzle[initRow + 2][initCol + 2] == value
            && ((initRow + 2) != row || (initCol + 2) != col)) {
        check = false;
    }

    if (check == true) {
        return true;
    } else {
        return false;
    }

}
public static void main(String[]args){
    String[][] puzzle = new String[9][9];
    fillBoard(puzzle);
    backTrack(puzzle);
}

Answer 1

此行不会“复制”数组

puzzle3 = puzzle2

您可以在puzzle2的同时初始化puzzle3：

int[][] puzzle2 = new int[9][9];
    int[][] puzzle3 = new int[9][9];
    for (int i = 0; i < 9; i++) {
        for (int i2 = 0; i2 < 9; i2++) {
            int v = Integer.parseInt(puzzle[i][i2]);
            puzzle2[i][i2] = v; //Takes the String puzzle and turns it into integers and adds it to puzzle2
            puzzle3[i][i2] = v;
        }
    }