Amazon Interview Question for SDE-3s


Country: United States
Interview Type: Phone Interview




Comment hidden because of low score. Click to expand.
1
of 1 vote

First can be solved by basic recursion.

void printSubsetsUtil(int a[], int i, int n, vector<int> &v, int sum)
{

    if(sum < 0 || i > n)
        return;

    if(sum == 0)
    {
        for(int j = 0; j < v.size(); j++)
            cout << v[j] << " ";
        cout << endl;
        return;
    }

    printSubsetsUtil(a, i+1, n, v, sum);

    v.push_back(a[i]);
    printSubsetsUtil(a, i+1, n, v, sum-a[i]);
    v.pop_back();

}

void printSubsets(int a[], int n, int sum)
{
    vector<int> v;
    printSubsetsUtil(a, 0, n, v, sum);
}
int main()
{
    int a[] = {1, 2, 3, 4, 5};

    int n = sizeof(a)/sizeof(a[0]);

    printSubsets(a, n, 5);

    return 0;
}

- gsharma34065 October 15, 2016 | Flag Reply
Comment hidden because of low score. Click to expand.
0
of 0 vote

void printSubsetsUtil(int a[], int i, int n, vector<int> &v, int sum)
{

if(sum < 0 || i > n)
return;

if(sum == 0)
{
for(int j = 0; j < v.size(); j++)
cout << v[j] << " ";
cout << endl;
return;
}

printSubsetsUtil(a, i+1, n, v, sum);

v.push_back(a[i]);
printSubsetsUtil(a, i+1, n, v, sum-a[i]);
v.pop_back();

}

void printSubsets(int a[], int n, int sum)
{
vector<int> v;
printSubsetsUtil(a, 0, n, v, sum);
}
int main()
{
int a[] = {1, 2, 3, 4, 5};

int n = sizeof(a)/sizeof(a[0]);

printSubsets(a, n, 5);

return 0;
}

- Anonymous October 18, 2016 | Flag Reply
Comment hidden because of low score. Click to expand.
0
of 0 vote

I made a solution for each problem in Java. Although I didn't test the code you can get the idea.

First problem:

public class Subsets{

private int size;
private int[] array;

private List<List<Integer>> results = new ArrayList<>();

public List<List<Integer>> subsets(int[] array, int target){
		size = array.length;
		this.array = array;	
		
		List<Integer> numbers = new LinkedList<>();
		subsets(0, target, numbers);

		return results;

}

public void subsets(int index, int target, List<Integer> numbers){
	if(target == 0){
		results.add(numbers);
	}else{
		if(index < size){
			subsets(index + 1, target - array[index], numbers;
			subsets(index + 1, target, new LinkedList<>();

		}
	}

}

}

Second one:

public class Subsets{

private int size;
private WorkItem[] array;

private int maximum;
private List<WorkItem> maximumList;

private List<WorkItem> workItems;

public List<WorkItem> subsets(WorkItem[] array, int money){
		size = array.length;
		this.array = array;

		
		workItems = new LinkedList<>();
		subsets(0, money, 0);

		return results;

}

public void subsets(int index, int money, int utility){
	if(index < size){

		subsets(index + 1, money, utility);
			
			WorkItem workItem = array[index];
			//We suppose that there are no negative costs
			if(money >= workItem.money){
				workItems.add(workItem);
			subsets(index + 1, money - workItem.money, utility + workItem.utility);
			workItems.remove(workItems.size() - 1);
}	
		
	}else{
		if(utility > maximum){
			maximum = utility;
			maximumList = new LinkedList<>();
			for(WorkItem workItem : workItems)
				maximumList.add(workItem);
		}

	}

}

}

Third one (I assume that WorkItem has a field "with", which contains the name and the utility of the related item:

public class Subsets{

private int size;
private WorkItem[] array;

private int maximum;
private List<WorkItem> maximumList;

private HashMap<String, WorkItem> workItems;

public List<WorkItem> subsets(WorkItem[] array, int money){
		size = array.length;
		this.array = array;

		
		workItems = new HashMap<>();
		subsets(0, money);

		return results;

}

public void subsets(int index, int money){
	if(index < size){

		subsets(index + 1, money);
			
			WorkItem workItem = array[index];
			//We suppose that there are no negative costs
			if(money >= workItem.money){
				workItems.put(workItem.name, workItem);	
				
			subsets(index + 1, money - workItem.money);
		
			workItems.remove(workItem.name);
}	
		
	}else{
		int utility = 0;
		for(WorkItem workItem : workItems.values()){
			if(workItem.with != null && workItems.containsKey(workItem.with.name))
				utility += workItem.with.utility;
			else
				utility += workItem.utility;

}

		if(utility > maximum){
			maximum = utility;
			maximumList = new LinkedList<>();
			for(WorkItem workItem : workItems.values())
				maximumList.add(workItem);
		}

	}

}

}

- libertythecoder October 18, 2016 | Flag Reply
Comment hidden because of low score. Click to expand.
0
of 0 vote

import java.util.ArrayList;
import java.util.List;

public class SubsetSum{

	public SubsetSum(int[] arr, int sum) {
		if (sum <= 0 ) {
			return;
		}
		subsetSumUtil(arr, 0, sum, new ArrayList<Integer>());	
	}

	public static void subsetSumUtil(int[]arr, int index, int sum, List<Integer> subset) {
		if (sum < 0) {
			return;
		}
		
		if (sum == 0){
			printList(subset);
		}
		
		for (int i = index; i < arr.length; ++i) {
			int indexInserted = subset.size();
			subset.add(arr[i]);
			subsetSumUtil(arr, i+1, sum- arr[i], subset);	
			subset.remove(indexInserted);		
		}
	}

	public static void printList(List<Integer> list){
		System.out.println(list.toString());
	}

	public static void main(String args[]){
		int[] arr = {1,2,3,4,5};
		int sum = 5;
		SubsetSum s = new SubsetSum(arr, sum);

	}


}

- gsAlgo October 25, 2016 | Flag Reply
Comment hidden because of low score. Click to expand.
0
of 0 vote

First one;

class SubSets{
    int[] array;
    SubSets(){
        array = new int[]{1,2,3,4,5};
    }
    
    public ArrayList<ArrayList<Integer>> getSubs(int totalNumber){
        ArrayList<ArrayList<Integer>> subArray = new ArrayList<ArrayList<Integer>>();
        ArrayList<Integer> tempSub = new ArrayList<Integer>();
        Integer currentTotal;
        for(int i = 0;i < array.length-1;i++){
            currentTotal = array[i];
            tempSub = new ArrayList<Integer>();
            tempSub.add(currentTotal);
            if (currentTotal < totalNumber) {
                for(int k = i+1; k < array.length;k++){
                    int t = k;
                    currentTotal = array[i];
                    tempSub = new ArrayList<Integer>();
                    tempSub.add(currentTotal);
                    while(currentTotal < totalNumber && t < array.length){
                        tempSub.add(array[t]);
                        currentTotal += array[t];
                        t++;
                    }
                    if (currentTotal == totalNumber) subArray.add(tempSub);
                }
            } 
            else if (currentTotal == totalNumber) subArray.add(tempSub);
        }
        
        return subArray;
    }
}

- edanir December 08, 2016 | Flag Reply
Comment hidden because of low score. Click to expand.
0
of 0 vote

public class Budget {

    int maxBudget, maxUtility;
    int[] cost, utility;
    String result;

    public Budget(int maxBudget, int[] cost, int[] utility) {

        this.maxBudget = maxBudget;
        this.cost = cost;
        this.utility = utility;
    }

    public static void main(String[] args) {

        int[] cost = {50, 10, 20, 5, 9};
        int[] utility = {50, 50, 50, 50, 50};
        int maxBudget = 25;

        Budget budget = new Budget(maxBudget, cost, utility);

        budget.calc();

        System.out.println("result: " + budget.result + " - maxUtility: " + budget.maxUtility);
    }

    private void calc() {

        calc(0, 0, 0, "");
    }

    private void calc(int cCost, int cUtility, int i, String s) {

        if (i >= cost.length)
            return;

        int tCost = cCost + cost[i];

        int tUtility = cUtility + utility[i];

        if (tCost <= maxBudget) {

            String tS = s + "," + i;

            calc(tCost, tUtility, i + 1, tS);

            if (tUtility > maxUtility) {
                maxUtility = tUtility;
                result = tS;
            }
        }
        calc(cCost, cUtility, i + 1, s);
    }

}

- vibhorrastogi.in January 27, 2017 | Flag Reply


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