Microsoft Interview Question for SDE1s


Country: United States
Interview Type: In-Person




Comment hidden because of low score. Click to expand.
2
of 2 vote

If all the elements are -ve than print the one having smallest magnitude
else
take into account only +ve numbers.

#include<iostream>
using namespace std;
void maxsum(int arr[],int size);
int main()
{
	int arr[] = {-23, -45, 78, 67, 45, 78, 23, -67, -45};
	int size = sizeof(arr)/sizeof(arr[0]);
	maxsum(arr,size);
	return 0;
}
void maxsum(int arr[],int size)
{
	int i,max;
	for(i=0;i<size;i++)
	{
		if(arr[i]>=0) break;
	}
	if(i==size)
	{
		max = arr[0];
		for(i=1;i<size;i++) 
		if(max<arr[i]) max = arr[i];
		cout <<max;
	}
	else
	{
		bool a[size];max = 0;
		for(i=0;i<size;i++) a[i] = false;
		for(i=0;i<size;i++)
		{
			if(arr[i]>=0)
			{
				a[i] = true;
				max += arr[i];
			}
		}
		cout<<"Max Sum = "<<max<<"\nAnd the sequence is...\n";
		for(i=0;i<size;i++)
		if(a[i]) cout<<arr[i]<<" ";
	}
}

- Sarthak Mall June 02, 2013 | Flag Reply
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0
of 0 votes

I think the question actually means you have to find *contiguous* numbers in the array that give the highest sum. That's what I get from it when he asks to find a "subsequence". Not to form one out of the elements.

- FoY January 26, 2014 | Flag
Comment hidden because of low score. Click to expand.
1
of 3 vote

public static find_max_subarray(int[] a) {
    // check arguments
    if(a == null || a.Length == 0) throw new ArgumentNullException();
    
    int max = a[0], tmp_max = a[0];
    foreach(var i in a) {
        if(tmp_max < 0) {
            tmp_max = i;
        } else {
            tmp_max += i;
        }
        max = tmp_max > max ? tmp_max : max;
    }
}

- SkyClouds May 06, 2013 | Flag Reply
Comment hidden because of low score. Click to expand.
-2
of 2 votes

hey buddy! check your code for {-6,2,-1,2,11} . It says 14.but answer is 13

- parthi May 30, 2013 | Flag
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1
of 3 votes

@skyclouds, nice solution; @parthi, you are totally wrong!

- veronica June 01, 2013 | Flag
Comment hidden because of low score. Click to expand.
0
of 0 vote

int main ()
{
  int arr[] = {-23, -45, 78, 67, 45, 78, 23, -67, -45};
  int max_sum = 0, max_pos = 0, max_sz = 0;
  int arr_sz = sizeof(arr)/sizeof(int);
  for(int i=0; i < arr_sz; i++)
  {
    int sum = 0;
    int cur_sz = arr_sz - i;
    for(int j=0; j < cur_sz; j++)
    {
      sum += arr[i + j];
      if(sum > max_sum)
      {
        max_sum = sum;
        max_pos = i;
        max_sz = j + 1;
      }
    }
  }

  for(int i = max_pos; i < max_pos+max_sz; i++)
    printf("%d ", arr[i]);
}

- Shaibujan May 06, 2013 | Flag Reply
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0
of 0 vote

int subseq (int array[], int length) {
    int sum[length], i, j, max;
    sum[0] = array[0];
    for (i=1;i<length;i++) {
        j = i - 1;
        while (j >= 0) {
            if (array[j] < array[i]
                && (sum[j] + array[j]) > sum[i]) {
                sum[i] = sum[j] + array[j];
            }
            --j;
        }
    }
    max = sum[0];
    for (i=1;i<length;i++) {
        if (max < sum[i]) 
            max = sum[i];
    }
    return max;
}

- Time Pass May 16, 2013 | Flag Reply
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0
of 0 vote

static int[] Subsequence(int[] A)
        {
            int maxStart = 0;
            int maxEnd = A.Length - 1;
            int maxSum = 0;

            int start = -1;
            int end = 0;
            int sum = 0;

            for(int i = 0; i < A.Length; i++)
            {
                if(A[i] >= 0 && start < 0)
                {
                    start = i; end = i; sum=A[i];
                }
                else if(A[i] >= 0 && start >= 0)
                {
                    end = i; sum += A[i];
                }
                else if (A[i] < 0 && start >= 0)
                {
                    if(sum > maxSum)
                    {
                        maxSum =sum;
                        maxStart= start;
                        maxEnd = end;
                    }

                    start = -1;
                }
            }

            //last sum
            if (start >= 0 && sum > maxSum)
            {
                maxSum = sum;
                maxStart = start;
                maxEnd = end;
            }

            return new int[]
            {
                maxSum,
                maxStart,
                maxEnd
            };
        }

- alexey May 18, 2013 | Flag Reply
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0
of 0 votes

great buddy

- parthi May 30, 2013 | Flag
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0
of 0 votes

1) it wont work for all negatives in array
2) it wont work if max subarray will include negatives as you have not taken negative values into consideration. (example given above by parthi, {-6,2,-1,2,11} ). Here max should be 14, your code will return 13

- saurabh June 08, 2013 | Flag
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0
of 0 vote

public static int MaxSequenceSum(int[] nums)
        {
            if (nums == null || nums.Length == 0)
            {
                throw new ArgumentException();
            }

            if (nums.Length == 1)
            {
                return nums[0];
            }

            int sum = 0;
            int maxSum = nums[0];
            int lastEnd = 0;

            for (int i = 0; i < nums.Length; i++)
            {
                if (nums[i] > 0 && lastEnd == i - 1)
                {
                    sum += nums[i];
                    ++lastEnd;
                }
                else if (nums[i] > 0 && lastEnd < i - 1)
                {
                    sum = nums[i];
                    lastEnd = i;
                }
                else if (nums[i] < 0)
                {
                    if (lastEnd != 0)
                    {
                        if (maxSum < sum)
                        {
                            maxSum = sum;
                        }
                    }
                    else
                    {
                        if (maxSum < nums[i])
                        {
                            maxSum = nums[i];
                        }
                    }
                }
            }

            return maxSum;
        }

- Anonymous June 05, 2013 | Flag Reply
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0
of 0 vote

Divided algo in few parts:
part 1:
1) get minimum negative value
2) get first positive sum of array
3) get start & end index of first positive sum
this will be current running sum
part 2:

1) get sum of all negative values
 2) get sum of all positive values
 3) compare current_sum with curr_sum + positive_sum + negative_sum
    if max_sum < (curr_sum + positive_sum + negative_sum)
        update max_sum
    else
        update curr_sum
    if max_sum < positive sum
        update max_sum with positive sum
4) also keep on updating indexes

I have written code, due to keep track of index, code has become little messy
please update me with compact code, if u have

void maxSubSeq (int *a, int n)
{
        int max = -1;
        int i = 0;
        int max_e_i = 0;
        int cur_s_i = 0;
        int cur_e_i = 0;
        int pos = 0;
        int neg = 0;
        int cur = -1;
        int max_s_i = -1;
        int l_n_v = -10000;
        int next_p_index = 0;
        int neg_i = 0;

        while (i < n)
        {
                if (a[i] < 0 && a[i] > l_n_v && cur < 0)
                {
                        l_n_v = a[i];
                        neg_i = i;
                        i++;
                        continue;
                }

                if (cur > 0 && a[i] < 0)
                        break;
                if (a[i] >= 0)
                {
                        cur = 0;
                        while (i < n && a[i] >= 0)
                        {
                                if (max_s_i < 0)
                                        max_s_i = i;
                                cur += a[i];
                                i++;
                        }
                        break;
                }
                i++;
        }
        if (cur >= 0)
        {
                max = cur;
                max_e_i = i-1;
        }

        while (i < n)
        {
                neg = 0;
                pos = 0;

                while (i < n && a[i] < 0)
                {
                        neg += a[i];
                        i++;
                }
                if (i < n)
                        next_p_index = i;

                while (i < n && a[i] > 0)
                {
                        pos += a[i];
                        i++;
                }

                if ((cur + neg + pos) > max)
                {
                        cur = max = cur+neg+pos;
                        cur_e_i = max_e_i = i-1;
                }
                else
                {
                        cur = cur+pos+neg;
                        cur_e_i = i-1;
                }
                if (max < pos)
                {
                        cur = max = pos;
                        cur_s_i = max_s_i = next_p_index;
                }
        }

        if (max == -1)
        {
                printf ("no Positive sum. Least negative value is: %d at index: %d\n", l_n_v, neg_i);
        }
        else
        {
                printf ("Max sum is: %d\n", max);
                printf ("Max SubSequence is: \n", max);
                for (i = max_s_i; i <= max_e_i; i++)
                        printf ("%d ", a[i]);
                printf ("\n");
        }
}

- saurabh June 08, 2013 | Flag Reply
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0
of 0 votes

I have run it for the following test cases:

int a[] = {-1,-2,1,3,11,-10,-3,1,-9,2,11,13,-11,25};
      int a[] = {10,11,-15,-20,2,3,-7,15,30,-1,10,-1,30};
      int a[] = {-20,-30,-40,-2,-9,-13};
      int a[] = {-20,-30,-40,-1,0,-9,-13};
      int a[] = {3,4,-3,1,-2,1,-1,-1,-1,-1,-1};
      int a[] = {3,4,-3,1,-2,25,-1,-1,-1,-1,-1};

Update me for other tricky cases :)

- saurabh June 08, 2013 | Flag
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0
of 0 votes

//@saurabh. Your code looks good but you have used too many variables. Here is a simple one. Mine doesn't work for all -ve numbers because you don't need to handle that case because you won't have a seq in -ve numbers.

int* subseq(int *array, int length) {
    int i = 0, max = 0;
    int* new_array = (int *)malloc(sizeof(int*(length+1)));
    new_array[0] = 0;
    if (array == NULL || length == 0)
        return;
    for(i=0;i<length;i++) {
        if((new_array[i] + array[i]) >= 0) {
            new_array[i+1] = new_array[i] + array[i]; 
            max = (max >= new_array[i+1]) ? max : new_array[i+1];
        }       
        else 
            new_array[i+1] = 0;       
    }    
    return new_array;
}

- Time Pass June 16, 2013 | Flag
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0
of 0 vote

This code find the max sum with the locations:

public void maxSubSeq(int[] data){
        int s = 0, a = 0, b = 0, sum = 0, maxSum = 0;
        for(int i = 0; i < data.length; i++){
            sum = sum + data[i];
            if(sum < 0){
                sum = 0;
                s = i + 1;
            }
            else if(sum > maxSum){
                maxSum = sum;
                a = s;
                b = i;
            }
        }
        System.out.println("Max sum is: " + maxSum + "  from location " + a + " to " + b);
    }

- Novice June 16, 2013 | Flag Reply
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0
of 0 vote

I don't understand your code. I think you need 3 loops. At least my Code works.

struct index
{
int index_left,index_right;
};

index findLargestSubsequence(int arr[],int len)
{
int index_left=0;
int index_right=0;
int max_sum=0;
int sum = 0;
index my_index;

for(int i = 0 ; i<len ; i++)
{
for( int k = i ;k<len ; k++)
{
for( int j = i ; j<=k ; j++)
{
sum += arr[j];
}

if(sum > max_sum)
{
max_sum = sum;
index_left = i;
index_right = k;
}
sum=0;
}
}
my_index.index_left = index_left;
my_index.index_right = index_right;
return my_index;
}

- Schedl August 01, 2013 | Flag Reply
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0
of 0 vote

public static long maxSumSequence(int[] arr){
long sum = arr[0];
long oldsum = arr[0];
for (int i = 1; i < arr.length; i++){
long newsum = arr[i], tempsum = sum + arr[i];
if(tempsum < sum){
if (oldsum < sum) oldsum = sum;
sum = newsum;
}else{
if ((newsum > tempsum) && (newsum > sum)) sum = newsum;
if ((tempsum > sum) && (tempsum > newsum)) sum = tempsum;
}
}
if (sum > oldsum)return sum;
return oldsum;
}

- Anonymous August 12, 2013 | Flag Reply


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