diff --git a/third.c b/third.c
new file mode 100644
index 0000000..513573d
--- /dev/null
+++ b/third.c
@@ -0,0 +1,103 @@
+#include <stdio.h>
+
+#define SIZE 9
+
+void printSudoku(int board[SIZE][SIZE]) {
+    for (int i = 0; i < SIZE; i++) {
+        for (int j = 0; j < SIZE; j++) {
+            if (j % 3 == 0 && j != 0) {
+                printf("| ");
+            }
+            if (board[i][j] == 0) {
+                printf(". "); // 用'.'表示空白
+            }
+            else {
+                printf("%d ", board[i][j]);
+            }
+        }
+        printf("\n");
+        if ((i + 1) % 3 == 0 && i != 8) {
+            printf("---------------------\n");
+        }
+    }
+}
+
+int isValidSudoku(int board[SIZE][SIZE]) {
+    int row[SIZE][SIZE] = { 0 }; // 行使用情况
+    int col[SIZE][SIZE] = { 0 }; // 列使用情况
+    int block[SIZE][SIZE] = { 0 }; // 3x3块使用情况
+
+    for (int i = 0; i < SIZE; i++) {
+        for (int j = 0; j < SIZE; j++) {
+            int num = board[i][j];
+            if (num != 0) {
+                int blockIndex = (i / 3) * 3 + (j / 3);
+
+                // 检查行
+                if (row[i][num - 1]) {
+                    printf("False: Invalid initial Sudoku matrix!\n");
+                    printf("The number %d in the row %d has been used!\n", num, i + 1);
+                    return 0; // 行重复，返回不合法
+                }
+                row[i][num - 1] = 1; // 标记该数字在行中使用过
+
+                // 检查列
+                if (col[j][num - 1]) {
+                    printf("False: Invalid initial Sudoku matrix!\n");
+                    printf("The number %d in the col %d has been used!\n", num, j + 1);
+                    return 0; // 列重复，返回不合法
+                }
+                col[j][num - 1] = 1; // 标记该数字在列中使用过
+
+                // 检查3x3块
+                if (block[blockIndex][num - 1]) {
+                    printf("False: Invalid initial Sudoku matrix!\n");
+                    printf("The number %d in the block %d has been used!\n", num, blockIndex + 1);
+                    return 0; // 块重复，返回不合法
+                }
+                block[blockIndex][num - 1] = 1; // 标记该数字在块中使用过
+            }
+        }
+    }
+    return 1; // 如果没有问题，返回合法
+}
+
+int main() {
+    int board0[SIZE][SIZE] = {
+        {5, 3, 0, 0, 7, 0, 0, 0, 0},
+        {6, 0, 0, 1, 9, 5, 0, 0, 0},
+        {0, 9, 8, 0, 0, 0, 0, 6, 0},
+        {8, 0, 0, 0, 6, 0, 0, 0, 3},
+        {4, 0, 0, 8, 0, 3, 0, 0, 1},
+        {7, 0, 0, 0, 2, 0, 0, 0, 6},
+        {0, 6, 0, 0, 0, 0, 2, 8, 0},
+        {0, 0, 0, 4, 1, 9, 0, 0, 5},
+        {0, 0, 0, 0, 8, 0, 0, 7, 9}
+    };
+
+    int board1[SIZE][SIZE] = {
+        {8, 3, 0, 0, 7, 0, 0, 0, 0},
+        {6, 0, 0, 1, 9, 5, 0, 0, 0},
+        {0, 9, 8, 0, 0, 0, 0, 6, 0},
+        {8, 0, 0, 0, 6, 0, 0, 0, 3},
+        {4, 0, 0, 8, 0, 3, 0, 0, 1},
+        {7, 0, 0, 0, 2, 0, 0, 0, 6},
+        {0, 6, 0, 0, 0, 0, 2, 8, 0},
+        {0, 0, 0, 4, 1, 9, 0, 0, 5},
+        {0, 0, 0, 0, 8, 0, 0, 7, 9}
+    };
+
+    printf("The original Sudoku matrix:\n");
+    printSudoku(board0);
+    if (isValidSudoku(board0)) {
+        printf("True: Valid initial Sudoku matrix!\n");
+    }
+
+    printf("\nThe original Sudoku matrix:\n");
+    printSudoku(board1);
+    if (isValidSudoku(board1)) {
+        printf("True: Valid initial Sudoku matrix!\n");
+    }
+
+    return 0;
+}
\ No newline at end of file