diff --git a/第三题.c b/第三题.c
new file mode 100644
index 0000000..1b994e8
--- /dev/null
+++ b/第三题.c
@@ -0,0 +1,165 @@
+#include <stdio.h>
+int sudoku[9][9];
+void print_sudoku(int sudoku[9][9]) {
+    for (int i = 0; i < 9; i++) {
+        if (i % 3 == 0 && i != 0) {
+            printf("-------------------------\n");
+        }
+        for (int j = 0; j < 9; j++) {
+            if (j % 3 == 0 && j != 0) {
+                printf("| ");
+            }
+            printf("%d ", sudoku[i][j]);
+        }
+        printf("\n");
+    }
+}
+int is_sudoku(int sudoku[9][9]) {
+    for (int i = 1; i <= 3; i++)
+    {
+        int num[10] = { 0 };
+        for (int j = 1; j <= 3; j++)
+        {
+            for (int k = 0; k < 9; k++)
+            {
+                num[(sudoku[i * j - 1][k])]++;
+                if (num[(sudoku[i * j - 1][k])] >1 && sudoku[i * j - 1][k] != 0)
+                {
+                    printf("False:Invalid initial Sudoku matrix!\n");
+                    for (int a = (i - 1) * 3; a <= i * j - 1; a++)
+                    {
+                        for (int c = 0; c < 9; c++)
+                        {
+                            if (sudoku[a][c] == sudoku[i * j - 1][k])
+                            {
+                                printf("The number %d in the col %d has been used!\n", sudoku[i * j - 1][k], a + 1);
+                                return 0;
+                            }
+                        }
+                    }
+                }
+            }
+
+        }
+        for (int l = 1; l < 10; l++)
+        {
+            if (num[l] < 1)
+            {
+                printf("False:Invalid initial Sudoku matrix!\n");
+                printf("The number %d has not been used\n", l);
+                return 0;
+            }
+        }
+    }
+    printf("True:Valid initial Sudoku matrix!\n");
+    return 1;
+}
+int findvalue(int sudoku[9][9], int i, int j)
+{
+    int m, n, k;
+    int temp[10] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
+    for (k = 1; k < 10; k++)
+    {
+        if (temp[sudoku[i][k - 1]] == 0)
+            temp[sudoku[i][k - 1]] = sudoku[i][k - 1];
+        if (temp[sudoku[k - 1][j]] == 0)
+            temp[sudoku[k - 1][j]] = sudoku[k - 1][j];
+    }
+    for (m = 0; m < 3; m++)
+        for (n = 0; n < 3; n++)
+            if (temp[sudoku[i / 3 * 3 + m][j / 3 * 3 + n]] == 0)
+                temp[sudoku[i / 3 * 3 + m][j / 3 * 3 + n]] = sudoku[i / 3 * 3 + m][j / 3 * 3 + n];
+    for (k = 1; k < 10; k++)
+        if (temp[k] == 0)
+        {
+            temp[0]++;
+            m = k;
+        }
+    if (temp[0] == 0)
+        return -1;
+    else if (temp[0] == 1)
+        return m;
+    else
+        return 0;
+}
+int main() {
+    int flag;
+    int sudoku[9][9] = { {0, 3, 0, 0, 0, 7, 0, 0, 0},
+
+  {1, 2, 5, 0, 0, 9, 4, 0, 0},
+
+  {0, 7, 9, 1, 0, 0, 0, 3, 0},
+
+  {0, 0, 6, 0, 8, 0, 0, 9, 1},
+
+  {0, 0, 0, 9, 5, 1, 0, 0, 0},
+
+  {9, 1, 0, 0, 7, 0, 5, 0, 0},
+
+  {0, 9, 0, 0, 0, 5, 7, 4, 0},
+
+  {0, 0, 8, 7, 0, 0, 2, 6, 9},
+
+  {0, 0, 0, 4, 0, 0, 0, 5, 0} };
+    printf("The original Sudoku matrix:\n");  
+    print_sudoku(sudoku);
+    if (!is_sudoku(sudoku))
+    {
+        printf("No solution!");
+        return 0;
+    }
+    if (is_sudoku(sudoku))
+    {
+        int i, j, temp, empty = 0;
+        for (i = 0; i < 9; i++)
+        {
+            for (j = 0; j < 9; j++)
+                if (sudoku[i][j] == 0)
+                    empty++;
+        }
+        while (empty)
+
+        {
+            for (i = 0; i < 9; i++)
+
+            {
+                for (j = 0; j < 9; j++)
+
+                {
+                    if (sudoku[i][j] == 0)
+
+                    {
+                        temp = findvalue(sudoku, i, j);
+
+                        if (temp == -1)
+
+                        {
+                            printf("No solution！\n");
+                            return 1;
+
+                        }
+
+                        sudoku[i][j] = temp;
+
+                        if (temp != 0)empty--;
+
+                    }
+
+                }
+
+            }
+
+        }
+        for (i = 0; i < 9; i++)
+
+        {
+            for (j = 0; j < 9; j++)
+
+                printf("%d ", sudoku[i][j]);
+
+            printf("\n");
+
+        }
+    }
+        return 0;
+}