【发布时间】：2019-06-06 10:04:49
【问题描述】：
我必须在大学的 sudoku.c 中实现递归求解方法。
我很努力，但我的所有实现都不起作用。
我是 c 编程的绝对新手，所以我对使用这个数独回溯算法感到绝望。
谁能帮帮我？
solve方法是空的，所以这个方法里面的一切都是我尝试的。
数独.h
#ifndef _SUDOKU_H_
#define _SUDOKU_H_
#define SIZE 9
#define SQRT_SIZE 3
void init(int begin[SIZE][SIZE]);
void print();
int checkValueInField(int value, int row, int col);
int setValueInField(int value, int row, int col);
int removeValueFromField(int row, int col);
int getValueFromField(int row, int col);
int solve(int row, int col);
#endif /* _SUDOKU_H_ */
数独.c
#include "sudoku.h"
#include <stdio.h>
#include <stdlib.h>
#include <memory.h>
#define SIZE 9
#define SQRT_SIZE 3
int field[SIZE][SIZE];
int initial[SIZE][SIZE];
/* Initializes the sudoku array.
* The field initial keeps the original start value for
* figuring out if a value is fixed or can be changed. */
void init(int begin[SIZE][SIZE]) {
memcpy(field, begin, SIZE * SIZE * sizeof(int));
memcpy(initial, begin, SIZE * SIZE * sizeof(int));
}
/* really pretty prints the sudoku array */
void print() {
int row, col;
// print the first line
printf("||");
for (col = 0; col < SIZE - 1; col++) {
if (col % SQRT_SIZE == SQRT_SIZE - 1)
printf("===++");
else
printf("===+");
}
printf("===||\n");
// loop through all rows of the array
for (row = 0; row < SIZE; row++) {
// print the line with field values
for (col = 0; col < SIZE; col++) {
if (col % SQRT_SIZE == 0)
printf("|| ");
else
printf("| ");
if (field[row][col] == 0)
printf(" ");
else
printf("%d ", field[row][col]);
}
// print the separation line;
// depending on the result of the modulo operation
// print a single or double line
printf("||\n||");
if (row % SQRT_SIZE == SQRT_SIZE - 1) {
for (col = 0; col < SIZE - 1; col++) {
if (col % SQRT_SIZE == SQRT_SIZE - 1)
printf("===++");
else
printf("===+");
}
printf("===||\n");
}
else {
for (col = 0; col < SIZE - 1; col++) {
if (col % SQRT_SIZE == SQRT_SIZE - 1)
printf("---++");
else
printf("---+");
}
printf("---||\n");
}
}
}
/* Checks if the value is valid and can be set into the field.
* The function returns false if the value is already present or
* has been one of the initial values. */
int checkValueInField(int value, int row, int col) {
int i, r, c;
int squareRow;
int squareCol;
// checks for initial values
if (initial[row][col] != 0) {
if (initial[row][col] == value)
return 1;
else
return 0;
}
// check horizontally
for (i = 0; i < SIZE; i++) {
if (field[row][i] == value) return 0;
}
// check vertically
for (i = 0; i < SIZE; i++) {
if (field[i][col] == value) return 0;
}
// check square
squareRow = row / SQRT_SIZE;
squareCol = col / SQRT_SIZE;
for (r = squareRow * SQRT_SIZE; r < squareRow * SQRT_SIZE + SQRT_SIZE; r++) {
for (c = squareCol * SQRT_SIZE; c < squareCol * SQRT_SIZE + SQRT_SIZE; c++) {
if (field[r][c] == value) return 0;
}
}
return 1;
}
/* Set a value in the sudoku field if the field is empty.
* The method returns false if the field contains a fixed number. */
int setValueInField(int value, int row, int col) {
if (initial[row][col] == 0) {
field[row][col] = value;
return 1;
}
else if (initial[row][col] == value)
return 1;
return 0;
}
/* Removes a value in the sudoku field if it doesn't contain an initial value.
* The method returns false if the field contains a fixed number and cannot be
* removed. */
int removeValueFromField(int row, int col) {
if (initial[row][col] == 0) {
field[row][col] = 0;
return 1;
}
return 0;
}
/* Returns the value in the field */
int getValueFromField(int row, int col) {
return field[row][col];
}
/* Return true if you've found a valid solution for the sudoku. Use the
* return value to abort the backtracking algorithm if you've found the
* first solution, otherwise you would search for a possible solution. */
int solve(int row, int col) {
/* Implement a backtracking for solving the sudoku */
for (int i = 1; i <= 9; i++) {
if ((checkValueInField(i, row, col)) == 1) {
setValueInField(i, row, col);
}
solve(row, col + 1);
solve(row + 1, col);
}
return 0;
}
main.c
#include <stdio.h>
#include "sudoku.h"
int main(int argc, char * const argv[]) {
int initial[SIZE][SIZE] = {
{0, 1, 0, 0, 0, 9, 0, 5, 0},
{0, 9, 0, 0, 0, 0, 4, 8, 0},
{0, 6, 0, 1, 0, 4, 0, 0, 0},
{0, 0, 5, 0, 0, 0, 9, 3, 0},
{0, 0, 0, 7, 0, 2, 0, 0, 0},
{0, 2, 1, 0, 0, 0, 8, 0, 0},
{4, 0, 0, 0, 8, 0, 6, 0, 9},
{0, 0, 0, 0, 6, 0, 5, 0, 3},
{2, 0, 0, 0, 3, 0, 0, 0, 0},
};
init(initial);
print();
solve(0, 0);
print();
return 0;
}
【问题讨论】：
-
一些提示：1) 仅当您实际找到要插入的有效值时才递归 2) 当您退出递归调用时再次删除该值，以便单元格可以用于下一次试试看。
-
我不太明白你的意思，我真的不知道该怎么办
-
@asynts 我相信这些文件大部分都没有动过，而练习是填充
solve函数的主体