add 036

Author: andavid

src/com/andavid/leetcode/_036/Solution.java

@@ -0,0 +1,56 @@
+import java.util.*;
+
+class Solution {
+  public boolean isValidSudoku(char[][] board) {
+    final int size = 9;
+
+    if (board == null || board.length != size || board[0].length != size) {
+      return false;
+    }
+
+    ArrayList<HashSet<Character>> row = new ArrayList<HashSet<Character>>();
+    ArrayList<HashSet<Character>> col = new ArrayList<HashSet<Character>>();
+    ArrayList<HashSet<Character>> area = new ArrayList<HashSet<Character>>();
+
+    for (int i = 0; i < size; i++) {
+      row.add(new HashSet<Character>());
+      col.add(new HashSet<Character>());
+      area.add(new HashSet<Character>());
+    }
+
+    for (int i = 0; i < size; i++) { // row
+      for (int j = 0; j < size; j++) { // column
+        int box = 3 * (i / 3) + j / 3; // sub box
+        if (board[i][j] != '.') {
+          if (row.get(i).contains(board[i][j])
+              || col.get(j).contains(board[i][j])
+              || area.get(box).contains(board[i][j])) {
+            return false;
+          }
+          row.get(i).add(board[i][j]);
+          col.get(j).add(board[i][j]);
+          area.get(box).add(board[i][j]);
+        }
+      }
+    }
+
+    return true;
+  }
+
+  public static void main(String[] args) {
+    Solution solution = new Solution();
+    char[][] board = {
+      {'.','8','7','6','5','4','3','2','1'},
+      {'2','.','.','.','.','.','.','.','.'},
+      {'3','.','.','.','.','.','.','.','.'},
+      {'4','.','.','.','.','.','.','.','.'},
+      {'5','.','.','.','.','.','.','.','.'},
+      {'6','.','.','.','.','.','.','.','.'},
+      {'7','.','.','.','.','.','.','.','.'},
+      {'8','.','.','.','.','.','.','.','.'},
+      {'9','.','.','.','.','.','.','.','.'}
+    };
+
+    System.out.println(solution.isValidSudoku(board));
+  }
+}