AlgoPlan0709

#rotate the stones
#key idea:
-consider stones moving right rather than moving down
-look for consecutive empty spots until we hit a non-empty spot.

class Solution {
    public char[][] rotateTheBox(char[][] box) {
        int m = box.length;
        int n = box[0].length;
        System.out.println(m);
        System.out.println(n);
        char[][] newbox =new char[n][m];

        int empty = n-1;
        for( int row = 0; row < m;row++){
            for (int col = n-1;col>=0;col--){
                if (box[row][col]=='#'){
                    empty= col+1;
                    //keeps moving right to find the rightest empty spot
                    while(empty <n && box[row][empty] =='.'){
                        empty++;
                    }
                    //hit a non-empty stop;
                    if(empty-1 < n && box[row][empty-1] =='.'){
                        box[row][empty-1] = '#';
                        box[row][col] = '.';
                   
                    }
 
                }
            }
        }
        for(int i = 0; i < m;i++){
            for (int j =0; j < n;j++){
                newbox[j][m-1-i] = box[i][j];
            }
        }
        return newbox;
    }
}

#valid sudoku
#key idea:
-go through the board according to the three rules.

class Solution {
    public boolean isValidSudoku(char[][] board) {
               boolean[] checked = new boolean[10];
        char temp ='.';
        //go through rows
        for (int i = 0;i < 9;i++){
            for (int k = 0; k< 9;k++){
                if(board[i][k] !='.' ){
                    temp = board[i][k];
                    if (!checked[(temp-'0')-1]){
                        checked[(temp-'0')-1] = true;
                    }else {
                        System.out.println(i + " "+ k);
                        return false;
                    }


                }
            }
            checked = new boolean[10];
        }
        checked = new boolean[10];
        //go through columns
    for (int i = 0; i < 9; i++) {
      for (int k = 0; k < 9; k++) {
        if (board[k][i] != '.') {
          temp = board[k][i];
          if (!checked[(temp - '0')]) {
            checked[(temp - '0')] = true;
          } else {
            System.out.println(i + " "+ k);
            return false;
          }
        }
      }
      checked = new boolean[10];
    }
    checked = new boolean[10];
    int box_int = 0;
    //go through boxes
    while (box_int<9){
        checked = new boolean[10];
        System.out.println(box_int);
        for (int k = 0; k < 3;k++){
            for (int m = 0;m < 3;m++){
                if (board[box_int+k][m]!='.'){
                    temp = board[box_int+k][m] ;
                    if (!checked[(temp-'0')]){
                        checked[(temp-'0')] = true;
                    }else {
                        System.out.println(k + " "+ m);
                        return false;
                    }
                }

            }
        }
        checked = new boolean[10];
        for (int k = 0; k < 3;k++){
            for (int m = 3;m < 6;m++){
                if (board[box_int+k][m]!='.'){
                    temp = board[box_int+k][m] ;
                    if (!checked[(temp-'0')]){
                        checked[(temp-'0')] = true;
                    }else {
                        System.out.println(k + " "+ m);
                        return false;
                    }
                }

            }
        }
            checked = new boolean[10];
        for (int k = 0; k < 3;k++){
            for (int m = 6;m < 9;m++){
                if (board[box_int+k][m]!='.'){
                    temp = board[box_int+k][m] ;
                    if (!checked[(temp-'0')]){
                        checked[(temp-'0')] = true;
                    }else {
                        System.out.println(k + " "+ m);
                        return false;
                    }
                }

            }

        
    }
            box_int = box_int+3;
        }
        return true;
    }
}

#contain all integers from 1 to n each row and column
class Solution {
    public boolean checkValid(int[][] matrix) {
        int n = matrix.length;
        //check rows
        boolean[] checked = new boolean[n+1];
        for (int i = 0; i < n;i++){
            for(int j = 0; j < n;j++){
                if (!checked[matrix[i][j]]){
                    checked[matrix[i][j]] = true;
                }else{
                    return false;
                }
            }
            checked = new boolean[n+1];
            
        }
        for (int i = 0; i < n;i++){
            for(int j = 0; j < n;j++){
                if (!checked[matrix[j][i]]){
                    checked[matrix[j][i]] = true;
                }else{
                    return false;
                }
            }
            checked = new boolean[n+1];
        
        }
        return true;
    }
}