Amazon Interview Question for SDE-2s


Country: United States
Interview Type: In-Person




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{
int input[n];
int min = input[n-1];
int max = input[0];
int sub_len = 0;
int e_idx = 0, s_idx = 0;
for(int i = 0; i < n-1; i++) {
if(input[n-i-1] < min) {
min = input[n-i-1];
} else {
s_idx = i;
}

if(input[i+1] > max) {
max = input[i+1];
} else {
e_idx = i;
}
}

if(e_idx > s_idx) {
sub_len = (e_idx - s_idx + 1);
}
}

- Pinkesh September 06, 2017 | Flag Reply
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Is it assumed that the array should be increasing?

- tiandiao123 September 07, 2017 | Flag Reply
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I am wondering whether the subarray should be consecutive or not consecutive?

- tiandiao123 September 07, 2017 | Flag Reply
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#include <iostream>

#define SZ 10

using namespace std;

int findsubArray(int arr[], int& b, int &e)
{
	int i, j, tb, te;

	b = SZ-1;
	e= -1;
	//Assuming the sorting is ascending
	//traverse as long as asending order is maintained
	for(i=1, j=0; i<SZ; i++) {
		if(arr[i] < arr[j]) {
		//its a glitch in sorting order
		//sub array sorting will be needed from the posizion where arr[i] fits
			tb = j;
			while(tb > -1 && arr[tb] > arr[i]) {
				tb --;
			}
			tb++;
			te = i;
			if(tb < b) {
				b = tb;
			}
			if(te > e) {
				e = te;
			}
			cout<<"b = " << b << " e = " << e <<endl;
		} else j = i;
	}
	return 0;
}

int main()
{
	int sb, se;
	int arr[10] = {0, 2, 5, 100, 3, 200, 1, 88, 300, 500};
	findsubArray(arr, sb, se);
}

- Anonymous September 15, 2017 | Flag Reply
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{{{ {{{ #include <iostream> #define SZ 10 using namespace std; int findsubArray(int arr[], int& b, int &e) { int i, j, tb, te; b = SZ-1; e= -1; //Assuming the sorting is ascending //traverse as long as asending order is maintained for(i=1, j=0; i<SZ; i++) { if(arr[i] < arr[j]) { //its a glitch in sorting order //sub array sorting will be needed from the posizion where arr[i] fits tb = j; while(tb > -1 && arr[tb] > arr[i]) { tb --; } tb++; te = i; if(tb < b) { b = tb; } if(te > e) { e = te; } cout<<"b = " << b << " e = " << e <<endl; } else j = i; } return 0; } int main() { int sb, se; int arr[10] = {0, 2, 5, 100, 3, 200, 1, 88, 300, 500}; findsubArray(arr, sb, se); } }}} }}} - Bob September 15, 2017 | Flag Reply
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Would not following code work?

public class UnSortedSubArray {
public static void main(String[] args) {
int[] array = {1,13,2,4,17, 15, 19, 20,22};
Stack<Integer> integers = new Stack<>();
int start = -1;;
int end = -1;;
integers.push(array[0]);
for(int i = 1; i<array.length;i++)
{
if(integers.peek() > array[i]){
if(start == -1)
start = i-1;
end = i;
}
else
{
integers.push(array[i]);
}


}

System.out.println(start + " " + end);
}
}

- Dumpy September 30, 2017 | Flag Reply
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pair<int, int> SortPatch(vector<int> const &a)
{
	if (a.empty()) {
		return pair<int, int>(-1, -1);
	}
	vector<int> min_to_right, max_to_left;
	min_to_right.resize(a.size());
	max_to_left.resize(a.size());

	int max_val = numeric_limits<int>::min();
	for (int i = 0; i < a.size(); ++i) {
		max_val = max(max_val, a[i]);
		max_to_left[i] = max_val;
	}

	int min_val = numeric_limits<int>::max();
	for (int i = a.size() - 1; i >= 0; --i) {
		min_val = min(min_val, a[i]);
		min_to_right[i] = min_val;
	}

	int i = 0;
	for (; i < a.size(); ++i) {
		if (a[i] > min_to_right[i]) {
			break;
		}
	}

	int j = a.size() - 1;
	for (; j >= 0; --j) {
		if (a[j] < max_to_left[j]) {
			break;
		}
	}

	if (i >= j) {
		return pair<int, int>(0, 0);
	}
	return pair<int, int>(i, j);
}

- Alex November 14, 2017 | Flag Reply
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This is insertion sort.
> if elements are already sorted, it won't make any swap

private static void doInsertionSort(int[] arr) {
		
		// Iterate through all cards : pick one each time
		for (int i = 1; i < arr.length; i++) {
			
			// say you have picked card called key
			int key = arr[i];
			int j = i-1;
			
			while(j >= 0 && arr[j] > key) {
				arr[j+1] = arr[j];
				j--;
			}
			// move fwd one and place key card
			arr[j+1] = key;
			
		}
		
	}

start of the unsorted array -> element for which line arr[j+1] = arr[j]; will start executing.
end of unsorted array -> element for which line arr[j+1] = arr[j]; will stop executing.

{start,....., end} will be min unsorted array.

There could be multiple such unsorted arrays. To find that, store all (start, end) and finally calculate one subarray with min length.

Time Complexity:- Since most of the elements are sorted, this will take between O(n) and O(n^2).

- Kunal Saxena January 25, 2018 | Flag Reply


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