3484: Design-Spreadsheet
Medium

table of contents

This question is basically just a simple implementation question.

The Spreadsheet itself is just a 2D array, with 26 vector<int> of size row+1:

class Spreadsheet {
public:
    Spreadsheet(int rows) {
        spreadsheet.resize(26, vector<int>(rows+1, 0));
    }

    // ...

private:
    vector<vector<int>> spreadsheet;

    // ...

};

To make the operations simpler to implement, I created two helper functions.

The first one that I implemented was returnCoordinate, which would return the numerical indices of a cell from its string representation.

pair<int, int> returnCoordinate (string cell) {
    int col = cell[0]-'A';
    int row = stoi(cell.substr(1, cell.size()-1));
    return {col, row};
}

Since equations always followed the format of =v1+v2, where v1 and v2, we can write a function parseVariable to convert v1 & v2 into numerical form, handling the cases where v1 & v2 are either non-negative integers or cell references:

int parseVariable(int index, string formula) {
    if (formula[index]-'0' >= 0 && formula[index]-'0' <= 9) {
        int endIndex = index;
        while (endIndex < formula.size() && formula[endIndex]-'0' >= 0 && formula[endIndex]-'0' <= 9) {
            ++endIndex;
        }
        return stoi(formula.substr(index, endIndex-index));
    } else {
        int endIndex = index;
        while(endIndex < formula.size() && formula[endIndex] != '+') {
            ++endIndex;
        }
        pair<int, int> coords = returnCoordinate(formula.substr(index, endIndex-index));
        return spreadsheet[coords.first][coords.second];
    }
}

Now, using the two helper functions, we can define all the other class functions.

For setCell, we can simply use returnCoordinate to update the respective cell in spreadsheet with value:

void setCell(string cell, int value) {
    pair<int, int> coords = returnCoordinate(cell);
    spreadsheet[coords.first][coords.second] = value;
}

For resetCell, we can do the same thing as setCell, except update the respective cell to a value of 0:

void resetCell(string cell) {
    pair<int, int> coords = returnCoordinate(cell);
    spreadsheet[coords.first][coords.second] = 0;
}

Finally for getValue, since we are always summing two values together, we can use our handy parseVariable function to get the firstVariable and secondVariable, and simply return the sum of both values:

int getValue(string formula) {
    int index = 1;
    int firstVariable = parseVariable(1, formula);
    int secondVariable = parseVariable(formula.find('+')+1, formula);
    return firstVariable + secondVariable;
}

code

class Spreadsheet {
public:
    Spreadsheet(int rows) {
        spreadsheet.resize(26, vector<int>(rows+1, 0));
    }
    
    void setCell(string cell, int value) {
        pair<int, int> coords = returnCoordinate(cell);
        spreadsheet[coords.first][coords.second] = value;
    }
    
    void resetCell(string cell) {
        pair<int, int> coords = returnCoordinate(cell);
        spreadsheet[coords.first][coords.second] = 0;
    }
    
    int getValue(string formula) {
        int index = 1;
        int firstVariable = parseVariable(1, formula);
        int secondVariable = parseVariable(formula.find('+')+1, formula);
        return firstVariable + secondVariable;
    }
private:
    vector<vector<int>> spreadsheet;
    pair<int, int> returnCoordinate (string cell) {
        int col = cell[0]-'A';
        int row = stoi(cell.substr(1, cell.size()-1));
        return {col, row};
    }
    int parseVariable(int index, string formula) {
        if (formula[index]-'0' >= 0 && formula[index]-'0' <= 9) {
            int endIndex = index;
            while (endIndex < formula.size() && formula[endIndex]-'0' >= 0 && formula[endIndex]-'0' <= 9) {
                ++endIndex;
            }
            return stoi(formula.substr(index, endIndex-index));
        } else {
            int endIndex = index;
            while(endIndex < formula.size() && formula[endIndex] != '+') {
                ++endIndex;
            }
            pair<int, int> coords = returnCoordinate(formula.substr(index, endIndex-index));
            return spreadsheet[coords.first][coords.second];
        }
    }
};

/**
 * 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

time taken