[Week06] BOJ 2580: 스도쿠

Author: whqtker

weekly/week06/BOJ_2580_스도쿠/whqtker.java

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+package ps_baekjoon;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.ArrayDeque;
+import java.util.Arrays;
+import java.util.Queue;
+import java.util.Stack;
+import java.util.StringTokenizer;
+import java.util.Vector;
+
+public class Main {
+	
+	static StringBuilder sb = new StringBuilder();
+	
+	static Vector<Coor> zeros = new Vector<>();
+	static int[][] arr;
+
+	static class Coor {
+		int x;
+		int y;
+		
+		Coor(int x, int y) {
+			this.x = x;
+			this.y = y;
+		}
+	}
+	
+	static void printArr() {
+		for (int i = 0; i < 9; i++) {
+			for (int j = 0; j < 9; j++) {
+				sb.append(arr[i][j]).append(' ');
+			}
+			sb.append("\n");
+		}
+		
+		System.out.println(sb);
+	}
+	
+	static boolean col(int num, int x, int y) {
+		for (int i = 0; i < 9; i++) {
+			if (arr[x][i] == num) {
+				return false;
+			}
+		}
+		
+		return true;
+	}
+	
+	static boolean row(int num, int x, int y) {
+		for (int i = 0; i < 9; i++) {
+			if (arr[i][y] == num) {
+				return false;
+			}
+		}
+		
+		return true;
+	}
+	
+	static boolean square(int num, int x, int y) {
+		int sx = (x / 3) * 3;
+		int sy = (y / 3) * 3;
+		
+		for (int i = sx; i < sx + 3; i++) {
+			for (int j = sy; j < sy + 3; j++) {
+				if (arr[i][j] == num) {
+					return false;
+				}
+			}
+		}
+		
+		return true;
+	}
+	
+	static boolean ok(int num, int x, int y) {
+		return col(num, x, y) && row(num, x, y) && square(num, x, y);
+	}
+	
+	static void dfs(int cnt) {
+		if (cnt == zeros.size()) {
+			printArr();
+			System.exit(0);
+		}
+		
+		Coor cur = zeros.get(cnt);
+		
+		for (int i = 1; i <= 9; i++) {
+			if (ok(i, cur.x, cur.y)) {
+				arr[cur.x][cur.y] = i;
+				
+				dfs(cnt + 1);
+				
+				arr[cur.x][cur.y] = 0;
+			}
+		}
+	}
+
+	public static void main(String[] args) throws IOException {
+		
+		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+		
+		arr = new int[9][9];
+		
+		for (int i = 0; i < 9; i++) {
+			String line = br.readLine();
+			StringTokenizer st = new StringTokenizer(line);
+			for (int j = 0; j < 9; j++) {
+				arr[i][j] = Integer.parseInt(st.nextToken());
+				
+				if (arr[i][j] == 0) {
+					zeros.add(new Coor(i, j));
+				}
+			}
+		}
+		
+		dfs(0);
+	}
+}