Solution.js

/**
 * @param {number} n
 * @return {number}
 */
var countNumbersWithUniqueDigits = function(n) {
    switch(n) {
        case 0: 
            return 1;
        case 1:
            return 10;
        case 2:
            return 91;
        case 3:
            return 739;
        case 4:
            return 5275;
        case 5:
            return 32491;
        case 6:
            return 168571;
        case 7:
            return 712891;
        case 8:
            return 2345851;
        case 9:
            return 5611771;
        default:
            return 8877691;
    }
};