20251110 baekjoon

code_study/Baekjoon/java/_2239.java

@@ -0,0 +1,70 @@
+import java.util.*;
+
+public class _2239 {
+    static int[][] board = new int[9][9];
+    static int[][] empties = new int[81][2];
+    static int empties_count = 0;
+
+    static boolean isPossible(int x, int y, int n) {
+        for(int i=0; i<9; i++) {
+            if(board[y][i] == n && i != x) return false;
+            if(board[i][x] == n && i != y) return false;
+
+            int nx = (x/3)*3 + i%3;
+            int ny = (y/3)*3 + i/3;
+            if(board[ny][nx] == n && !(nx==x && ny==y)) return false;
+        }
+
+        return true;
+    }
+
+    static void printBoard() {
+        for(int[] row : board) {
+            for(int n : row) {
+                System.out.printf("%d", n);
+            }
+            System.out.printf("\n");
+        }
+    }
+
+    static void backTracking(int depth) {
+        if(depth == empties_count) {
+            printBoard();
+            System.exit(0);
+        }
+
+        int cx = empties[depth][0];
+        int cy = empties[depth][1];
+
+        for(int n=1; n<=9; n++) {
+            if(isPossible(cx, cy, n)) {
+                board[cy][cx] = n;
+                backTracking(depth+1);
+                board[cy][cx] = 0;
+            }
+        }
+
+        return;
+    }
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+
+        for(int i=0; i<9; i++) {
+            board[i] = sc.nextLine().chars()
+                                    .map(c->c-'0')
+                                    .toArray();
+            
+            for (int j=0; j<9; j++) {
+                if(board[i][j]==0) {
+                    empties[empties_count][0] = j;
+                    empties[empties_count][1] = i;
+                    empties_count++;
+                }
+            }
+        }
+
+        sc.close();
+
+        backTracking(0);
+    }
+}