【算法 C】Leetcode 36. Valid Sudoku 有效的数独

其实算法并没有太难，无论是3次遍历还是1次遍历，都不会超时，我在做的时候，如何使用测试数据反而困扰了我很久。

读取测试数据

将测试数据放在文件中读取，这里将文件指针改为stdin应该也是一样的效果。

#include <stdio.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>

int main()
{
    int boardSize = 9;
    int boardColSize = 9;
    char** board = (char **) malloc(sizeof(char *) * boardSize);

    // 打开文件
    FILE *fp = fopen("sudoku1.txt", "r");
    if (fp == NULL)
    {
        fprintf(stderr, "读取文件出错");
        exit(-1);
    }

    // 输出文件内容
    printf("文件内容为：\n");
    int ch;
    while ((ch = fgetc(fp)) != EOF)
    {
        putchar(ch);
    }
    printf("\n");

    // 读取数组
    rewind(fp);
    for (int i = 0; i < boardSize; i++)
    {
        board[i] = (char *) malloc(sizeof(char) * boardSize);  // 每行分配内存
        for (int j = 0; j < boardColSize; j++)
        {
            while ((ch = fgetc(fp)) != EOF && ch != '\"');
            board[i][j] = fgetc(fp);
            fgetc(fp);
        }
    }
    fclose(fp);

    // 输出查看数组
    printf("读取到数组为: \n");
    for (int i = 0; i < boardSize; i++)
    {
        for (int j = 0; j < boardColSize; j++)
        {
            printf("%c ", board[i][j]);
        }
        printf("\n");
    }

    // solve
    bool validate = isValidSudoku(board, boardSize, &boardColSize);
    puts(validate ? "true": "false");
    // 释放内存
    for (int i = 0; i < boardSize; i++)
    {
        free(board[i]);
    }
    free((void *) board);
    return 0;
}

3次遍历

#include <stdio.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
bool isValidSudoku(char** board, int boardSize, int* boardColSize)
{
    int nums[10] = {0};
    int tmp;
    // 检查行
    for(int i = 0; i < boardSize; i++)
    {
        memset(nums, 0, sizeof(int) * 10);
        for(int j = 0; j < *boardColSize; j++)
        {
            tmp = board[i][j];
            if (tmp <= '9' && tmp > '0')
            {
                tmp = board[i][j] - '0';
                nums[tmp] += 1;
                if (nums[tmp] > 1)
                {
//					printf("false原因(行): [%d, %d]", i, j);
                    return false;
                }
            }

        }
    }
    // 检查列
    for(int j = 0; j < *boardColSize; j++)
    {
       memset(nums, 0, sizeof(int) * 10);
        for(int i = 0; i < boardSize; i++)
        {
            tmp = board[i][j];
            if (tmp <= '9' && tmp > '0')
            {
                tmp = board[i][j] - '0';
                nums[tmp] += 1;
                if (nums[tmp] > 1)
                {
//                	printf("false原因(列): [%d, %d]", i, j);
                    return false;
                }
            }

        }
    }
    // 检查九宫格
    for (int i = 0; i < boardSize / 3; i++)
    {
        for (int j = 0; j < *boardColSize / 3; j++)
        {
            memset(nums, 0, sizeof(int) * 10);
            for (int k = 0; k < 3; k++)
            {
                for (int l = 0; l < 3; l++)
                {
                    tmp = board[i * 3 + k][j * 3 + l];
                    if (tmp <= '9' && tmp > '0')
                    {
                        tmp = tmp - '0';
                        nums[tmp] += 1;
                        if (nums[tmp] > 1)
                        {
//                        	printf("false原因9: [%d, %d]", i * 3 + k, j * 3 + l);
                            return false;
                        }
                    }
                }
            }
        }
    }
    return true;
}

int main()
{
    int boardSize = 9;
    int boardColSize = 9;
    char** board = (char **) malloc(sizeof(char *) * boardSize);

    // 打开文件
    FILE *fp = fopen("sudoku1.txt", "r");
    if (fp == NULL)
    {
        fprintf(stderr, "读取文件出错");
        exit(-1);
    }

    // 输出文件内容
    printf("文件内容为：\n");
    int ch;
    while ((ch = fgetc(fp)) != EOF)
    {
        putchar(ch);
    }
    printf("\n");

    // 读取数组
    rewind(fp);
    for (int i = 0; i < boardSize; i++)
    {
        board[i] = (char *) malloc(sizeof(char) * boardSize);  // 每行分配内存
        for (int j = 0; j < boardColSize; j++)
        {
            while ((ch = fgetc(fp)) != EOF && ch != '\"');
            board[i][j] = fgetc(fp);
            fgetc(fp);
        }
    }
    fclose(fp);

    // 输出查看数组
    printf("读取到数组为: \n");
    for (int i = 0; i < boardSize; i++)
    {
        for (int j = 0; j < boardColSize; j++)
        {
            printf("%c ", board[i][j]);
        }
        printf("\n");
    }

    // solve
    bool validate = isValidSudoku(board, boardSize, &boardColSize);
	puts(validate ? "true": "false");
    // 释放内存
    for (int i = 0; i < boardSize; i++)
    {
        free(board[i]);
    }
    free((void *) board);
    return 0;
}

一次遍历

#include <stdio.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
bool isValidSudoku(char** board, int boardSize, int* boardColSize)
{

    /* 一次遍历 */
    int row[9][9] = {0};
    int col[9][9] = {0};
    int box[9][9] = {0};
    int boxIndex;
    int tmp;
    for (int i = 0; i < 9; i++)
    {
        for (int j = 0; j < 9; j++)
        {
            tmp = board[i][j];
            if (tmp >='1' && tmp <= '9')
            {
                tmp -= '1';
                boxIndex = (i / 3) * 3 + j / 3;
                row[i][tmp] += 1;
                col[j][tmp] += 1;
                box[boxIndex][tmp] += 1;

                if (row[i][tmp] > 1 || col[j][tmp] > 1 || box[boxIndex][tmp] > 1)
                {
                    return false;
                }
            }

        }
    }

    return true;
}

int main()
{
    int boardSize = 9;
    int boardColSize = 9;
    char** board = (char **) malloc(sizeof(char *) * boardSize);

    // 打开文件
    FILE *fp = fopen("sudoku1.txt", "r");
    if (fp == NULL)
    {
        fprintf(stderr, "读取文件出错");
        exit(-1);
    }

    // 输出文件内容
    printf("文件内容为：\n");
    int ch;
    while ((ch = fgetc(fp)) != EOF)
    {
        putchar(ch);
    }
    printf("\n");

    // 读取数组
    rewind(fp);
    for (int i = 0; i < boardSize; i++)
    {
        board[i] = (char *) malloc(sizeof(char) * boardSize);  // 每行分配内存
        for (int j = 0; j < boardColSize; j++)
        {
            while ((ch = fgetc(fp)) != EOF && ch != '\"');
            board[i][j] = fgetc(fp);
            fgetc(fp);
        }
    }
    fclose(fp);

    // 输出查看数组
    printf("读取到数组为: \n");
    for (int i = 0; i < boardSize; i++)
    {
        for (int j = 0; j < boardColSize; j++)
        {
            printf("%c ", board[i][j]);
        }
        printf("\n");
    }

    // solve
    bool validate = isValidSudoku(board, boardSize, &boardColSize);
    puts(validate ? "true": "false");
    // 释放内存
    for (int i = 0; i < boardSize; i++)
    {
        free(board[i]);
    }
    free((void *) board);
    return 0;
}