Design Spreadsheet

public class Spreadsheet {
    // T.C. = O(n)
    // S.C. = O(n)
    HashMap<String, Integer> map; // cell --> cellvalue

    public Spreadsheet(int rows) {
        map = new HashMap<>();
    }
    
    public void setCell(String cell, int value) {
        map.put(cell, value);
    }
    
    public void resetCell(String cell) {
        map.put(cell, 0);
    }
    
    public int getValue(String formula) {
        // "=X+Y"

        String arr[] = formula.substring(1).split("\\+");

        return getCell(arr[0]) + getCell(arr[1]);

        
    }
    // =5+6, cell = "5"
    // 

    public int getCell(String cell) {
        if(cell.charAt(0)>='0' && cell.charAt(0)<='9') {
            return Integer.parseInt(cell);
        }
        else return map.getOrDefault(cell,0);
    }
}

/**
 * Your Spreadsheet object will be instantiated and called as such:
 * Spreadsheet obj = new Spreadsheet(rows);
 * obj.setCell(cell,value);
 * obj.resetCell(cell);
 * int param_3 = obj.getValue(formula);

    A B C D E F G ........ X Y Z
 1  10 0 0 0 0 0  ....      0 0 0
 2  0 15 0 0 0 0  ....      0 0 0
 3
 .
 .
 .
 n  0 0 0 0 0 0  ....      0 0 0

 */ {
    
}