valid sudoku leetcode solution in java
class Solution {
public boolean isValidSudoku(char[][] board) {
if(board == null || board.length == 0)
return false;
HashMap<Integer,Integer> [] rows = new HashMap[9];
HashMap<Integer,Integer> [] cols = new HashMap[9];
HashMap<Integer,Integer> [] boxes = new HashMap[9];
for(int i = 0; i < 9 ; i++){
rows[i] = new HashMap<Integer,Integer>();
cols[i] = new HashMap<Integer,Integer>();
boxes[i] = new HashMap<Integer,Integer>();
}
int num =0;
for(int i =0 ; i < 9 ; i++){
for(int j=0; j < 9; j++){
char n = board[i][j];
if(board[i][j] != '.'){
num = (int)n;
int box_index = (i/3)*3 + j/3;
rows[i].put(num,rows[i].getOrDefault(num,0)+1);
cols[j].put(num,cols[j].getOrDefault(num,0)+1);
boxes[box_index].put(num,boxes[box_index].getOrDefault(num,0)+1);
if(rows[i].get(num) > 1 || cols[j].get(num) > 1 || boxes[box_index].get(num) > 1)
return false;
}
}
}
return true;
}
}