数独解答，解答,import java.

数独解答，解答,import java.

import java.util.Scanner;public class Sudoku2 {    private static boolean isValid(int[][] sudo, int x, int y) {        boolean valid = true;        for (int i = 0; i < 9; i++) {            for (int j = 0; j < 9; j++) {                boolean condition = false;                condition = (i == x) || (j == y);//same row or same column                condition = condition || ((i / 3 == x / 3) && (j / 3 == y / 3));//same square                condition = condition && !((i == x) && (j == y));                if (condition && sudo[i][j] == sudo[x][y]) {                    valid = false;                }            }        }        return valid;    }    private static boolean findAnswer(int[][] sudo, int i, int j) {        if (i >= 9 || j >= 9) return true;        if (sudo[i][j] != 0) {//如果当前格子是已经填过的，直接进入下一个            if (j < 8) {                return findAnswer(sudo, i, j + 1);            } else {                return findAnswer(sudo, i + 1, 0);            }        }        boolean result = false;        int k = 1;        for (k = 1; k <= 9; k++) {//依次检验1-9看是否符合            sudo[i][j] = k;            if (isValid(sudo, i, j)) {                if (j < 8) {                    result = findAnswer(sudo, i, j + 1);                } else {                    result = findAnswer(sudo, i + 1, 0);                }            }            if (result) {//如果已经找到正解了不要在循环下去，不过这样只能找到一个答案                break;            }        }        if (k > 9 && !result) {//如果1-9都不符合，说明之前的格子有填错的，回溯，要把当前格子重置为0，一开始忘了这步导致debug了好久            sudo[i][j] = 0;//no answer, reset to 0 before backward....        }        return result;    }    private static void output(int[][] sudo) {        for (int i = 0; i < 9; i++) {            for (int j = 0; j < 9; j++) {                System.out.printf("%d ", sudo[i][j]);            }            System.out.println();        }    }    public static void main(String[] args) {        int[][] sudo = new int[9][9];        Scanner in = new Scanner(System.in);        for (int i = 0; i < 9; i++) {            for (int j = 0; j < 9; j++) {                sudo[i][j] = in.nextInt();            }        }        long start = System.nanoTime();        findAnswer(sudo, 0, 0);        System.out.printf("Sudoku2 takes time:%.2f\\n", (System.nanoTime() - start) / 1E9);        output(sudo);    }}//该片段来自于http://byrx.net