sudoku validator

bool numberChecker(string curr){
    vector<bool> numbers = { true, false, false, false, false, false, false, false, false, false };
    for (auto& c : curr) {
        int num = c - '0';
        if (numbers[num] == true) return false;
        numbers[num] = true;
    }
    for (int i = 1; i < numbers.size(); ++i) if (numbers[i] == false) return false;
    return true;
}

bool solution(vector<vector<int>> grid) {
    for (int i = 0; i < 9; ++i) {
        string currRow;
        for (int j = 0; j < 9; ++j) {
            currRow += grid[i][j] + '0';
        }
        if (!numberChecker(currRow)) return false;
    }

    for (int i = 0; i < 9; ++i) {
        string currCol;
        for (int j = 0; j < 9; ++j) {
            currCol += grid[j][i] + '0';
        }
        if (!numberChecker(currCol)) return false;
    }
    int rounds = 9;
    int sX = 0, eX = 2, sY = 0, eY = 2;
    while (rounds--) {
        string block;
        for (int i = sX; i <= eX; ++i) {
            for (int j = sY; j <= eY; ++j) {
                block += grid[i][j] + '0';
            }
        }
        if (!numberChecker(block)) return false;
        if (rounds == 8) { sX = 0; eX = 2; sY = 3; eY = 5; }
        if (rounds == 7) { sX = 0; eX = 2; sY = 6; eY = 8; }
        if (rounds == 6) { sX = 0; eX = 2; sY = 0; eY = 2; }
        if (rounds == 5) { sX = 3; eX = 5; sY = 3; eY = 5; }
        if (rounds == 4) { sX = 3; eX = 5; sY = 6; eY = 8; }
        if (rounds == 3) { sX = 3; eX = 5; sY = 0; eY = 2; }
        if (rounds == 2) { sX = 6; eX = 8; sY = 3; eY = 5; }
        if (rounds == 1) { sX = 6; eX = 8; sY = 6; eY = 8; }
    }
    return true;
}