diff --git a/t4.cpp b/t4.cpp
deleted file mode 100644
index e6d5b4f..0000000
--- a/t4.cpp
+++ /dev/null
@@ -1,189 +0,0 @@
-#include <stdio.h>
-int f[9] = {0}, copy[9][9] = {0};
-int t1[9][9] = {0}, t2[9][9] = {0}, t3[9][9] = {0};
-// int board[9][9] = {{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 board[9][9] = {{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}};
-int board[9][9] = {{5, 2, 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 ifans = 0;
-void f1()
-{
-    printf("|");
-    for (int i = 0; i < 23; i++)
-    {
-        printf("-");
-    }
-    printf("|\n");
-}
-void operate()
-{
-    for (int i = 0; i < 9; i++)
-    {
-        if (i % 3 == 0)
-        {
-            f1();
-        }
-        printf("| ");
-        for (int j = 0; j < 9; j++)
-        {
-            if (j % 3 == 0 && j)
-            {
-                printf("| ");
-            }
-            printf("%d ", board[i][j]);
-        }
-        printf("|\n");
-    }
-    f1();
-}
-int judge()
-{
-    for (int i = 0; i < 9; i++)
-    {
-        for(int j = 0; j < 9; j++)
-        {
-            if (board[i][j])
-            {
-                t1[i][board[i][j] - 1]++;
-                t2[j][board[i][j] - 1]++;
-                t3[(i / 3) * 3 + j / 3][board[i][j] - 1]++;
-            }
-        }
-    }
-    for (int i = 0; i < 9; i++)
-    {
-        for (int num = 0; num < 9; num++)
-        {
-            if (t1[i][num] > 1)
-            {
-                printf("False:Invalid initial Sudoku matrix!\n");
-                printf("      The number %d in the row %d has been used!\n", num + 1, i + 1);
-                printf("No solution!");
-                return 0;
-            }
-            else if (t2[i][num] > 1)
-            {
-                printf("False:Invalid initial Sudoku matrix!\n");
-                printf("      The number %d in the col %d has been used!\n", num + 1, i + 1);
-                printf("No solution!");
-                return 0;
-            }
-            else if (t3[i][num] > 1)
-            {
-                printf("False:Invalid initial Sudoku matrix!\n");
-                printf("      The number %d in the block %d has been used!\n", num + 1, i + 1);
-                printf("No solution!");
-                return 0;
-            }
-        }
-    }
-    printf("True:Valid initial Sudoku matrix!\n");
-    return 1;
-}
-void fill(int x, int y)
-{
-    int num;
-    if (x == 9 && y == 0)
-    {
-        printf("The solution of Sudoku matrix:\n");
-        operate();
-        ifans = 1;
-    }
-    else
-    {
-        if (copy[x][y])
-        {
-            if (y == 8)
-            {
-                fill(x + 1, 0);
-                if (x == 0 && y == 0 && ifans == 0)
-                {
-                    printf("No solution!");
-                }
-                return;
-            }
-            else{
-                fill(x, y + 1);
-                if (x == 0 && y == 0 && ifans == 0)
-                {
-                    printf("No solution!");
-                }
-                return;
-            }
-        }
-        else
-        {
-            for(num = 1; num <= 9; num++)
-            {
-                if (t1[x][num - 1] == 0 && t2[y][num - 1] == 0 && t3[(x / 3) * 3 + y / 3][num - 1] == 0)
-                {
-                    board[x][y] = num;
-                    t1[x][num - 1] = 1;
-                    t2[y][num - 1] = 1;
-                    t3[(x / 3) * 3 + y / 3][num - 1] = 1;
-                    if (y == 8)
-                    {
-                        // operate();
-                        fill(x + 1, 0);
-                        board[x][y] = 0;
-                        t1[x][num - 1] = 0;
-                        t2[y][num - 1] = 0;
-                        t3[(x / 3) * 3 + y / 3][num - 1] = 0;
-                    }
-                    else{
-                        // operate();
-                        fill(x, y + 1);
-                        board[x][y] = 0;
-                        t1[x][num - 1] = 0;
-                        t2[y][num - 1] = 0;
-                        t3[(x / 3) * 3 + y / 3][num - 1] = 0;
-                    }
-                }
-            }
-            if (x == 0 && y == 0 && ifans == 0)
-            {
-                printf("No solution!");
-            }
-            return;
-        }
-    }
-}
-int main()
-{
-    printf("The original Sudoku matrix:\n");
-    operate();
-    for (int i = 0; i < 9; i++)
-    {
-        for (int j = 0; j < 9; j++)
-        {
-            copy[i][j] = board[i][j];
-        }
-    }
-    if(judge())
-    {
-        fill(0,0);
-    }
-}
\ No newline at end of file