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main and 4.c

@@ -0,0 +1,98 @@
+#include<stdio.h>
+int main()
+{
+	void function1();
+	void function2();
+	void function3();
+	void function4();
+	return 0;
+	function1();
+	function2();
+	function3();
+	function4();
+}
+
+
+#include <stdio.h>
+
+int sudoku[9][9];
+
+
+int in_row(int row, int num) {
+    for (int i = 0; i < 9; i++) {
+        if (sudoku[row][i] == num) {
+            return 1;
+        }
+    }
+    return 0;
+}
+
+
+int in_col(int col, int num) {
+    for (int i = 0; i < 9; i++) {
+        if (sudoku[i][col] == num) {
+            return 1;
+        }
+    }
+    return 0;
+}
+
+
+int in_box(int row, int col, int num) {
+    int box_row = row / 3 * 3;
+    int box_col = col / 3 * 3;
+    for (int i = box_row; i < box_row + 3; i++) {
+        for (int j = box_col; j < box_col + 3; j++) {
+            if (sudoku[i][j] == num) {
+                return 1;
+            }
+        }
+    }
+    return 0;
+}
+
+
+int is_valid(int row, int col, int num) {
+    return !in_row(row, num) && !in_col(col, num) && !in_box(row, col, num);
+}
+
+
+int solve_sudoku(int row, int col) {
+    if (row == 9) {
+        return 1;
+    }
+    if (col == 9) {
+        return solve_sudoku(row + 1, 0);
+    }
+    if (sudoku[row][col] != 0) { 
+        return solve_sudoku(row, col + 1);
+    }
+    for (int num = 1; num <= 9; num++) { 
+        if (is_valid(row, col, num)) {
+            sudoku[row][col] = num;
+            if (solve_sudoku(row, col + 1)) {
+                return 1;
+            }
+            sudoku[row][col] = 0; 
+        }
+    }
+    return 0;
+}
+
+void function4()
+{
+    function1();
+    if (solve_sudoku(0, 0)) {
+        
+        for (int i = 0; i < 9; i++) {
+            for (int j = 0; j < 9; j++) {
+                printf("%d ", sudoku[i][j]);
+            }
+            printf("\n");
+        }
+    }
+    else {
+        printf("No solution!\n");
+    }
+    return 0;
+}