Reflections on five programming problems every Software Engineer should be able to solve in less than 1 hour

README.md

Reflections

Although I love these kind of problems I am aware that they are problematic in an interview situation.

Reginald Braithwaite eloquently described some of the more problematic points in Carnac the magnificient

solutions.js

(function problem1(){
    var list = [1, 2, 3, 4, 5]; // sum is 15

    function sumFor(aList) {
	var sum = 0;
	for (var index = 0; index < aList.length; index++) {
	    sum += aList[index];
	}
	return sum;
    }

    function sumWhile(aList) {
	var sum = 0, index = 0;
	while (index < aList.length) {
	    sum += aList[index++];
	}
	return sum;
    }

    function sumRecursion(aList) {
	if (aList.length == 0){
	    return 0;
	} else {
	    return aList[0] + sumRecursion(aList.slice(1));
	}
    }

    function sumReduce(aList) {
	return aList.reduce(function(acc, el){ return acc + el}, 0);
    }

    console.log(sumFor(list));
    console.log(sumWhile(list));
    console.log(sumRecursion(list));
    console.log(sumReduce(list));
})();

(function problem2(){
    function zip(as, bs){
	var result = [], index = 0;
	while (index < as.length && index < bs.length) {
	    result.push(as[index]);
	    result.push(bs[index]);
	    index++;
	}
	return result;
    };

    console.log(zip(['a','b','c'], [1, 2, 3]));

})();

(function problem3(){
    function fibonacci(n){
	var result = [];
	var a = 0, b = 1;
	while (n > 0) {
	    result.push(a);
	    var tmp = a;
	    a = b;
	    b = tmp + a;
	    n--;
	}
	return result;
    };

    console.log(fibonacci(100));

})();

(function problem4(){
    function significateDigit(n) {
	return parseInt(("" + n).split("")[0]);
    }

    function decreasing(a, b) {
	return significateDigit(b) - significateDigit(a);
    }

    function toString(element) {
	return "" + element;
    }

    function concat(accumalator, element){
	return accumalator + element;
    }

    function largestNumber(aList){
	return parseInt(aList.sort(decreasing).map(toString).reduce(concat));
    };

    console.log(largestNumber([50, 2, 1, 9]));
})();

(function problem5(){
    var options = ["-", "", "+"];

    function multiOptions(n) {
	if (n == 0) {
	    return [[]];
	} else {
	    var result = [];
	    multiOptions(n - 1).forEach(function(candidate){
		console.log()
		options.forEach(function(option){
		    var copy = candidate.slice(0);
		    copy.push(option);
		    result.push(copy);
		});
	    });
	    return result;
	}
    };

    function zip(as, bs){
	var result = [], index = 0;
	while (index < as.length && index < bs.length) {
	    result.push(as[index]);
	    result.push(bs[index]);
	    index++;
	}
	return result;
    };

    function expression(candidate) {
	var numbers = candidate.map(function(_, index){ return index + 1});
	var expr = zip(numbers, candidate).reduce(function(acc, element){
	    return acc + element;
	}) + (numbers[numbers.length - 1] + 1);
	return expr;
    }

    console.log(multiOptions(8)
		.map(expression)
		.map(function(expr){
		    return [expr, eval(expr)];
		})
		.filter(function(tuple){
		    return tuple[1] == 100
		})
		.map(function(tuple){
		    return tuple[0];
		}));
})();