题解 | #Sudoku#

#include <stdio.h>
int ccnt = 0;
int path[81][2];
void putinbuffer(int buffer[], int a[][9], int pattern, int  row, int  col) {
    int block = row / 3 * 3 + col / 3;
    if (pattern == 1) //row
        for (int i = 0; i < 9; i++) {
            if (a[row][i] != 0)
                buffer[(a[row][i])-1] ++;
        }
    if (pattern == 2) { //col
        for (int i = 0; i < 9; i++) {
            if (a[i][col] != 0)
                buffer[a[i][col]-1] ++;
        }
    }
    if (pattern == 3) { //block
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 3; j++) {
                if (a[block /3 * 3 + i][block % 3* 3 + j] != 0)
                    buffer[a[block / 3 * 3 + i][block % 3 * 3 + j]-1]++;
            }
        }
    }
}
void bufferclear(int buffer[]) {
    for (int i = 0; i < 9; i++) {
        buffer[i] = 0;
    }
}
void get_usabledata(int a[][9], int  row, int  col, int data[]) {
    int buff1[9]={0}, buff2[9]={0}, buff3[9]={0};
    putinbuffer(buff1, a, 1, row, col);
    putinbuffer(buff2, a, 2, row, col);
    putinbuffer(buff3, a, 3, row, col);
    int cnt1 = 0, cnt2 = 0, cnt3 = 0, cnt = 0;
    int data1[9]={0};
    int data2[9]={0};
    int data3[9]={0};
    for (int i = 0; i < 9; i++) {
        if (buff1[i] == 0) {
            data1[cnt1] = i+1;
            cnt1++;
        }
        if (buff2[i] == 0) {
            data2[cnt2] = i+1;
            cnt2++;
        }
        if (buff3[i] == 0) {
            data3[cnt3] = i+1;
            cnt3++;
        }

    }
    for (int cn1 = 0; cn1 <cnt1; cn1++) {
        for (int cn2 = 0; cn2 <cnt2; cn2++) {
            if (data1[cn1] == data2[cn2]) {
                for (int cn3 = 0; cn3 < cnt3; cn3++) {
                    if (data1[cn1] == data3[cn3]) {
                        data[cnt] = data1[cn1];
                        //printf("%d ",data[cnt]);
                        cnt++;
                        break;
                    }
                }
            }
        }
    }
}
int check_mode(int a[][9], int row, int col) {
    int data[9]={0};
    for (int i = 1; i < 4; i++) {
        bufferclear(data);
        putinbuffer(data, a, i, row, col);
        for (int j = 0; j < 9; j++) {
            if (data[j] > 1)
                return 0;
        }
    }
    return 1;
}
int dfs(int b[][9], int c[][2], int d[][9], int point) {
    //填入，检查
    //如果检查ok，节点下一层,不ok，另外的参数填入
    //如果该层所有参数都不通过，返回上层
    int i = 0;
    int dfstrue = 0;
    while (d[point][i] != 0) {
        b[c[point][0]][c[point][1]] = d[point][i];
        if (check_mode(b, c[point][0], c[point][1]) == 1) {
            path[point][0] = c[point][0];
            path[point][1] = c[point][1];
            if (point < (ccnt-1))
                dfstrue = dfs(b, c, d, point + 1);
            else
                return 1;
            if (dfstrue == 1)
                return 1;
        }
        i++;
    }
    b[c[point][0]][c[point][1]] = 0;
    return 0;
}
int main() {
    int a[9][9];
    int temp;
    for (int i = 0; i < 9; i++) {
        for (int j = 0; j < 9; j++) {
            if (scanf("%d ", &temp) != EOF)
                a[i][j] = temp;
        }
    }
    int c[81][2];
    int d[81][9] = {0};
    int data[9];
    for (int i = 0; i < 9; i++) {
        for (int j = 0; j < 9; j++) {
            bufferclear(data);
            if (a[i][j] == 0) {
                c[ccnt][0] = i;
                c[ccnt][1] = j;
                get_usabledata(a, i, j, data);
                for (int i = 0; i < 9; i++) {
                    if (data[i] > 0) {
                        d[ccnt][i] = data[i];
                    } else
                        break;
                }
                ccnt++;
            }
        }
    }
    int thetrue = dfs(a, c, d, 0);
    for (int i = 0; i < 9; i++) {
        for (int j = 0; j < 9; j++) {
            printf("%d ", a[i][j]);
        }
        printf("\n");
    }
    return 0;
}