diff --git a/program4_random.c b/program4_random.c
new file mode 100644
index 0000000..b53e82d
--- /dev/null
+++ b/program4_random.c
@@ -0,0 +1,285 @@
+//#include <stdio.h>
+//#include <stdbool.h>
+//#include <stdlib.h>
+//#include <time.h>
+//
+//// 打印数独矩阵
+//void printMatrix(int matrix[9][9]) {
+//    for (int i = 0; i < 9; i++) {
+//        if (i == 0 || i == 3 || i == 6) {
+//            printf("|-----------------------|\n");
+//        }
+//        for (int j = 0; j < 9; j++) {
+//            if (j == 0 || j == 3 || j == 6) {
+//                printf("| ");
+//            }
+//            if (matrix[i][j] == 0) {
+//                printf(". ");
+//            }
+//            else {
+//                printf("%d ", matrix[i][j]);
+//            }
+//            if (j == 8) {
+//                printf("|\n");
+//            }
+//        }
+//        if (i == 8) {
+//            printf("|-----------------------|\n");
+//        }
+//    }
+//}
+//
+//// 判断数字是否在某行中出现
+//int isInRow(int matrix[9][9], int row, int num) {
+//    for (int i = 0; i < 9; i++) {
+//        if (matrix[row][i] == num) {
+//            return 1;
+//        }
+//    }
+//    return 0;
+//}
+//
+//// 判断数字是否在某 3x3 子矩阵中出现
+//int isInGroup(int matrix[9][9], int startRow, int startCol, int num) {
+//    for (int i = 0; i < 3; i++) {
+//        for (int j = 0; j < 3; j++) {
+//            if (matrix[startRow + i][startCol + j] == num) {
+//                return 1;
+//            }
+//        }
+//    }
+//    return 0;
+//}
+//
+//// 判断数字是否在某行中已被使用
+//bool usedInRow(int matrix[9][9], int row, int num) {
+//    for (int col = 0; col < 9; col++) {
+//        if (matrix[row][col] == num) {
+//            return true;
+//        }
+//    }
+//    return false;
+//}
+//
+//// 判断数字是否在某列中已被使用
+//bool usedInCol(int matrix[9][9], int col, int num) {
+//    for (int row = 0; row < 9; row++) {
+//        if (matrix[row][col] == num) {
+//            return true;
+//        }
+//    }
+//    return false;
+//}
+//
+//// 判断数字是否在某 3x3 子矩阵中已被使用
+//bool usedInBox(int matrix[9][9], int boxStartRow, int boxStartCol, int num) {
+//    for (int row = 0; row < 3; row++) {
+//        for (int col = 0; col < 3; col++) {
+//            if (matrix[row + boxStartRow][col + boxStartCol] == num) {
+//                return true;
+//            }
+//        }
+//    }
+//    return false;
+//}
+//
+//// 判断在特定位置放置特定数字是否安全
+//bool isSafe(int matrix[9][9], int row, int col, int num) {
+//    return!usedInRow(matrix, row, num) && !usedInCol(matrix, col, num) && !usedInBox(matrix, row - row % 3, col - col % 3, num);
+//}
+//
+//// 查找空位置
+//bool findEmptyLocation(int matrix[9][9], int* row, int* col) {
+//    for (*row = 0; *row < 9; (*row)++) {
+//        for (*col = 0; *col < 9; (*col)++) {
+//            if (matrix[*row][*col] == 0) {
+//                return true;
+//            }
+//        }
+//    }
+//    return false;
+//}
+//
+//// 解决数独问题
+//bool solveSudoku(int matrix[9][9]) {
+//    int row, col;
+//    if (!findEmptyLocation(matrix, &row, &col)) {
+//        return true; // 数独已解决
+//    }
+//    for (int num = 1; num <= 9; num++) {
+//        if (isSafe(matrix, row, col, num)) {
+//            matrix[row][col] = num;
+//            if (solveSudoku(matrix)) {
+//                return true;
+//            }
+//            matrix[row][col] = 0; // 回溯
+//        }
+//    }
+//    return false;
+//}
+//
+//// 检查行是否符合数独规则
+//bool checkRows(int matrix[9][9]) {
+//    for (int i = 0; i < 9; i++) {
+//        int count[9] = { 0 };
+//        for (int j = 0; j < 9; j++) {
+//            if (matrix[i][j] > 0 && matrix[i][j] <= 9) {
+//                int num = matrix[i][j] - 1;
+//                if (count[num] > 0) {
+//                    return false;
+//                }
+//                count[num]++;
+//            }
+//        }
+//    }
+//    return true;
+//}
+//
+//// 检查列是否符合数独规则
+//bool checkColumns(int matrix[9][9]) {
+//    for (int j = 0; j < 9; j++) {
+//        int count[9] = { 0 };
+//        for (int i = 0; i < 9; i++) {
+//            if (matrix[i][j] > 0 && matrix[i][j] <= 9) {
+//                int num = matrix[i][j] - 1;
+//                if (count[num] > 0) {
+//                    return false;
+//                }
+//                count[num]++;
+//            }
+//        }
+//    }
+//    return true;
+//}
+//
+//// 检查 3x3 子矩阵是否符合数独规则
+//bool checkSubMatrices(int matrix[9][9]) {
+//    for (int row = 0; row < 9; row += 3) {
+//        for (int col = 0; col < 9; col += 3) {
+//            int count[9] = { 0 };
+//            for (int i = row; i < row + 3; i++) {
+//                for (int j = col; j < col + 3; j++) {
+//                    if (matrix[i][j] > 0 && matrix[i][j] <= 9) {
+//                        int num = matrix[i][j] - 1;
+//                        if (count[num] > 0) {
+//                            return false;
+//                        }
+//                        count[num]++;
+//                    }
+//                }
+//            }
+//        }
+//    }
+//    return true;
+//}
+//
+//// 判断整个矩阵是否是有效的数独矩阵
+//bool isSudokuMatrix(int matrix[9][9]) {
+//    return checkRows(matrix) && checkColumns(matrix) && checkSubMatrices(matrix);
+//}
+//
+//int main() {
+//    printf("The original Sudoku matrix: \n");
+//    srand(time(NULL));
+//    int matrix[9][9] = { 0 };
+//    int numbers[9] = { 1, 2, 3, 4, 5, 6, 7, 8, 9 };
+//
+//    for (int group = 0; group < 3; group++) {
+//        int usedNumbers[9] = { 0 };
+//        for (int i = 0; i < 9; i++) {
+//            usedNumbers[i] = numbers[i];
+//        }
+//
+//        for (int i = 0; i < 9; i++) {
+//            int idx = rand() % (9 - i);
+//            int temp = usedNumbers[idx];
+//            usedNumbers[idx] = usedNumbers[8 - i];
+//            usedNumbers[8 - i] = temp;
+//        }
+//
+//        for (int row = 0; row < 3; row++) {
+//            int count = 0;
+//            while (count < 3) {
+//                int num;
+//                do {
+//                    int idx = rand() % 9;
+//                    num = usedNumbers[idx];
+//                } while (num == 0 || isInRow(matrix, group * 3 + row, num) || isInGroup(matrix, group * 3, 0, num));
+//
+//                int pos;
+//                do {
+//                    pos = rand() % 9;
+//                } while (matrix[group * 3 + row][pos] != 0);
+//
+//                matrix[group * 3 + row][pos] = num;
+//                count++;
+//            }
+//        }
+//    }
+//
+//    for (int row = 0; row < 9; row++) {
+//        int uniqueNumbers[9] = { 0 };
+//        int uniqueCount = 0;
+//        for (int i = 0; i < 9; i++) {
+//            if (matrix[row][i] != 0 && !uniqueNumbers[matrix[row][i] - 1]) {
+//                uniqueNumbers[matrix[row][i] - 1] = 1;
+//                uniqueCount++;
+//            }
+//        }
+//        if (uniqueCount > 3) {
+//            while (uniqueCount > 3) {
+//                int idx = rand() % 9;
+//                if (matrix[row][idx] != 0 && uniqueNumbers[matrix[row][idx] - 1]) {
+//                    matrix[row][idx] = 0;
+//                    uniqueCount--;
+//                }
+//            }
+//        }
+//        else if (uniqueCount < 3) {
+//            while (uniqueCount < 3) {
+//                int num;
+//                do {
+//                    num = rand() % 9 + 1;
+//                } while (uniqueNumbers[num - 1]);
+//                int idx;
+//                do {
+//                    idx = rand() % 9;
+//                } while (matrix[row][idx] != 0);
+//                matrix[row][idx] = num;
+//                uniqueNumbers[num - 1] = 1;
+//                uniqueCount++;
+//            }
+//        }
+//    }
+//
+//    printMatrix(matrix);
+//    bool valid = isSudokuMatrix(matrix);
+//    if (valid) {
+//        printf("True:Valid initial Sudoku matrix!\n");
+//        if (solveSudoku(matrix)) {
+//            printf("The solution of Sudoku matrix:\n");
+//            printMatrix(matrix);
+//        }
+//        else {
+//            printf("No solution!\n");
+//        }
+//    }
+//    else {
+//        printf("False:Invalid initial Sudoku matrix!\n");
+//        for (int j = 0; j < 9; j++) {
+//            int count[9] = { 0 };
+//            for (int i = 0; i < 9; i++) {
+//                if (matrix[i][j] > 0 && matrix[i][j] <= 9) {
+//                    int num = matrix[i][j] - 1;
+//                    if (count[num] > 0) {
+//                        printf("The number %d in the col %d has been used!\n", matrix[i][j], j);
+//                        break;
+//                    }
+//                    count[num]++;
+//                }
+//            }
+//        }
+//        printf("No solution!\n");
+//    }
+//    return 0;
+//}
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