3797. Design Spreadsheet¶

Difficulty: Medium

3797. Design Spreadsheet

Medium

A spreadsheet is a grid with 26 columns (labeled from 'A' to 'Z') and a given number of rows. Each cell in the spreadsheet can hold an integer value between 0 and 10⁵.

Implement the Spreadsheet class:

Spreadsheet(int rows) Initializes a spreadsheet with 26 columns (labeled 'A' to 'Z') and the specified number of rows. All cells are initially set to 0.
void setCell(String cell, int value) Sets the value of the specified cell. The cell reference is provided in the format "AX" (e.g., "A1", "B10"), where the letter represents the column (from 'A' to 'Z') and the number represents a 1-indexed row.
void resetCell(String cell) Resets the specified cell to 0.
int getValue(String formula) Evaluates a formula of the form "=X+Y", where X and Y are either cell references or non-negative integers, and returns the computed sum.

Note: If getValue references a cell that has not been explicitly set using setCell, its value is considered 0.

Example 1:

Input:
["Spreadsheet", "getValue", "setCell", "getValue", "setCell", "getValue", "resetCell", "getValue"]
[[3], ["=5+7"], ["A1", 10], ["=A1+6"], ["B2", 15], ["=A1+B2"], ["A1"], ["=A1+B2"]]

Output:
[null, 12, null, 16, null, 25, null, 15]

Explanation

Spreadsheet spreadsheet = new Spreadsheet(3); // Initializes a spreadsheet with 3 rows and 26 columns
spreadsheet.getValue("=5+7"); // returns 12 (5+7)
spreadsheet.setCell("A1", 10); // sets A1 to 10
spreadsheet.getValue("=A1+6"); // returns 16 (10+6)
spreadsheet.setCell("B2", 15); // sets B2 to 15
spreadsheet.getValue("=A1+B2"); // returns 25 (10+15)
spreadsheet.resetCell("A1"); // resets A1 to 0
spreadsheet.getValue("=A1+B2"); // returns 15 (0+15)

Constraints:

1 <= rows <= 10³
0 <= value <= 10⁵
The formula is always in the format "=X+Y", where X and Y are either valid cell references or non-negative integers with values less than or equal to 10⁵.
Each cell reference consists of a capital letter from 'A' to 'Z' followed by a row number between 1 and rows.
At most 10⁴ calls will be made in total to setCell, resetCell, and getValue.

Solution¶

class Spreadsheet {
    private int arr[][];
    public Spreadsheet(int rows) {
        arr = new int[rows + 1][27];
    }

    public void setCell(String cell, int value) {
        int col = cell.charAt(0) - 'A';
        int row = 0;
        for (int i = 1; i < cell.length(); i++) 
            row = row * 10 + cell.charAt(i) - '0'; 
        arr[row][col] = value;
    }

    public void resetCell(String cell) {
        int col = cell.charAt(0) - 'A';
        int row = 0;
        for (int i = 1; i < cell.length(); i++)
            row = row * 10 + cell.charAt(i) - '0';
        arr[row][col] = 0; 
    }

    public int getValue(String formula) {
        /* Either first character can be a digit or first character can denote some column */
        formula = formula.substring(1, formula.length());
        if (!Character.isDigit(formula.charAt(0))) {
            //if it it not a digit
            int total = 0;
            int col1 = formula.charAt(0) - 'A';
            int row1 = 0, idx = -1;
            for (int i = 1; i < formula.length(); i++) {
                if (formula.charAt(i) == '+') {
                    idx = i;
                    break;
                }
                row1 = row1 * 10 + formula.charAt(i) - '0';
            }
            total += arr[row1][col1];

            //second half;
            // Again it could be some value or may denote to some cell;
            if (!Character.isDigit(formula.charAt(idx + 1))) {
                int col2 = formula.charAt(idx + 1) - 'A';
                int row2 = 0;
                for (int i = idx + 2; i < formula.length(); i++) {
                    row2 = row2 * 10 + formula.charAt(i) - '0';
                }
                total += arr[row2][col2];
            }
            else {
                int ans2 = 0;
                for (int i = idx + 1; i < formula.length(); i++) {
                    ans2 = ans2 * 10 + formula.charAt(i) - '0';
                }
                total += ans2;
            }
            return total;
        }       
        else {
            // first half is containg the value;
            int total = 0, idx = -1;
            for (int i = 0; i < formula.length(); i++) {
                if (formula.charAt(i) == '+') {
                    idx = i;
                    break;
                } 
                total = total * 10 + formula.charAt(i) - '0'; 
            }

            //second half 
            if (!Character.isDigit(formula.charAt(idx + 1))) {
                int col2 = formula.charAt(idx + 1) - 'A';
                int row2 = 0;
                for (int i = idx + 2; i < formula.length(); i++) {
                    row2 = row2 * 10 + formula.charAt(i) - '0';
                }
                total += arr[row2][col2];
            }
            else {
                int ans2 = 0;
                for (int i = idx + 1; i < formula.length(); i++) {
                    ans2 = ans2 * 10 + formula.charAt(i) - '0';
                }
                total += ans2;
            }
            return total;
        }
    }
}

/**
 * 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);
 */

Complexity Analysis¶

Time Complexity: O(?)
Space Complexity: O(?)

Approach¶

Detailed explanation of the approach will be added here