第七课选做题。

07/Optional05.c

@@ -0,0 +1,55 @@
+#include <stdio.h>
+#include <stdbool.h>
+
+int numbers[10] = { 0 };
+int cube[3][3] = { 0 };
+
+void output() {
+	int i = 0, j = 0;
+	for (i = 0; i < 3; i++) {
+		for (j = 0; j < 3; j++) {
+			printf("%d", cube[i][j]);
+			printf(" ");
+		}
+		printf("\n");
+	}
+	printf("\n");
+}
+
+void pickNext(int row, int col) {
+	int i = 0;
+	if (row == 2 && col == 2) {
+		for (int i = 1; i <= 9; i++) {
+			if (numbers[i] == false) {
+				cube[2][2] = i;
+				break;
+			}
+		}
+		if ((cube[0][0] + cube[0][1] + cube[0][2] == 15)
+			&& (cube[1][0] + cube[1][1] + cube[1][2] == 15)
+			&& (cube[0][0] + cube[1][0] + cube[2][0] == 15)
+			&& (cube[0][1] + cube[1][1] + cube[2][1] == 15)
+			&& (cube[0][0] + cube[1][1] + cube[2][2] == 15)
+			&& (cube[0][2] + cube[1][1] + cube[2][0] == 15)) {
+			output();
+		}
+	}
+	for (i = 1; i <= 9; i++) {
+		if (numbers[i] == false) {
+			numbers[i] = true;
+			cube[row][col] = i;
+			if (col == 2) {
+				pickNext(row + 1, 0);
+			}
+			else {
+				pickNext(row, col + 1);
+			}
+			numbers[i] = false;
+		}
+	}
+}
+
+int main() {
+	pickNext(0, 0);
+	return 0;
+}