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program2.c

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+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+
+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]);
+            }
+        }
+        printf("|\n");
+    }
+    printf("|-----------------------|\n");
+}
+
+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;
+}
+
+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;
+}
+
+int main() {
+    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);
+
+    return 0;
+}