CareerCup

This is a simple dynamic programming problem. It is similar to Kadane's largest subarray sum problem.

{
public int getLongestArithmeticSeq(int[] array) {
	int difference = array[1] - array[0];		// common difference of arithmetic sequence
	int longestLength = Integer.MIN_VALUE;	// stores the longest length sequence found till now
	int currentLength = 1;		// stores length of current arithmetic sequence
	for(int iii = 1; iii < array.length - 1; iii++) {
		int currentDifference = array[iii + 1] - array[iii];
		if (currentDifference == difference) {		// check if these elements are part of the sequence
			currentLength++;		// if they are, increase currentLenght
		} else {			// otherwise set currentLength to 1, and common difference to new difference
			currentLength = 1;
			difference = currentDifference;
		}
		longestLength = Math.max(longestLength, currentLength);		// store the maximum length
	}
	return longestLength;
}

}

Dear Pintu Gupta , Please post the questions clearly so that even beginners like me can also understand

#include<iostream>
using namespace std;
#include<stdlib.h>
#include<conio.h>
#include<string.h>
#include<math.h>

int glas(int *a,int n)
{
int i,j,k;
if(n==1||n==2)
{
return n;
}
else
{
i=j=k=0;
int d=a[1]-a[0];
int max=-1;
int count=2;
for(int i=1;i<n;)
{
count=2;
while((i+1<n)&&a[i+1]-a[i]==d)
{
count++;
i++;

}
if(max<count)
{
max=count;

}
d=a[i+1]-a[i];
i++;
}
return max;
}


}

int main()
{
int n;
cin>>n;
int *a=new int[n];

for(int i=0;i<n;i++)
cin>>a[i];
cout<<glas(a,n);
getch();
return 0;
}

if only continuous sequence is require then output of 2nd test case should be 4 not 5.
correct me if I`m wrong.

def find_max_seq(a):
    count = 0
    cur_count = 0
    for i in range(1,len(a)):
        if a[i]-a[i-1] == 1:
            cur_count += 1
        else:
            cur_count = 0
        if cur_count > count:
            count = cur_count
    return count+1 if count > 0 else count

if __name__ == '__main__':
    print find_max_seq([3,2,5,8])
    print find_max_seq([-1,1,3,7,11,15,19,20,21,22])
    print find_max_seq([-2,-1,0,1,2,3,7,11,15,19,20,21,22])

wtf does it mean? plz clarify this

public static int getElementNumofSequence(int[] a){
		int diff = a[1] - a[0];
		int diff2 = 0;
		int max=0, count =1;
		for(int i=1; i<a.length -1; i++) {
			diff2 = a[i+1] - a[i];
			if (diff == diff2) {
				count++;				
			} else {
				diff = diff2;
				if (max < count)
					max = count;
				count = 1;
			}
		}
		
		return max+1;
	}

c code please

def find_consective(num):
        num.sort()
        length = max_length = 1
        prev = num[0]
        for i in range(1, len(num)):
              if num[i] - prev ==  1:
                      length += 1
                      max_length = max(max_length, length)
              else:
                      length = 1
         return max_length

This problem can be solved using arithmetic sequence formula too.
a_n = a_1 + (n-1)d

we calculate a_1 and d from first two elements and then go for finding third element. by using the above formula and compare it with the current element of the array. If it matches, then we increment sequenceCount, if not, we reset all the set of variables.

public class LargestArithmeticSequenceInGiveArray {

int sequenceCount = 0;
int longestSequenceCount = 0;
int a_1 = 0;
int d = 0;

int indexCount = 0;
//a_n = a_1 + (n-1)d
public int findLongestArithmeticSequence(int[] givenArray)
{
if(givenArray.length <3)
{
return longestSequenceCount;
}

for(int i=0; i<givenArray.length;)
{
if(sequenceCount == 0)
{
a_1 = givenArray[i];
d = givenArray[i+1] - a_1;
sequenceCount++;
i++;
}
else if(sequenceCount>0)
{
if(a_1 + (sequenceCount)*d == givenArray[i])
{
sequenceCount++;
i++;
}
else
{
indexCount++;
if(longestSequenceCount < sequenceCount)
{
longestSequenceCount = sequenceCount;
}
sequenceCount=0;
i = indexCount;
}
}

if(i == givenArray.length)
{
if(sequenceCount > longestSequenceCount)
longestSequenceCount = sequenceCount;
}


}
return longestSequenceCount;
}


public static void main(String[] args) {
//-1 1 3 7 11 15 19 20 21 22
int[] givenNumber = new int[10];
givenNumber[0] = -1;
givenNumber[1] = 1;
givenNumber[2] = 3;
givenNumber[3] = 7;
givenNumber[4] = 11;
givenNumber[5] = 15;
givenNumber[6] = 19;
givenNumber[7] = 20;
givenNumber[8] = 21;
givenNumber[9] = 22;

LargestArithmeticSequenceInGiveArray l = new LargestArithmeticSequenceInGiveArray();
System.out.println(l.findLongestArithmeticSequence(givenNumber));
}

}

public class LargestArithmeticSequenceInGiveArray {

	int sequenceCount = 0;
	int longestSequenceCount = 0;
	int a_1 = 0;
	int d = 0;
	
	int indexCount = 0;
	//a_n = a_1 + (n-1)d 
	public int findLongestArithmeticSequence(int[] givenArray)
	{
		if(givenArray.length <3)
		{
			return longestSequenceCount;
		}
		
		for(int i=0; i<givenArray.length;)
		{
			if(sequenceCount == 0)
			{
				a_1 = givenArray[i];
				d = givenArray[i+1] - a_1;
				sequenceCount++;
				i++;
			}
			else if(sequenceCount>0)
			{
				if(a_1 + (sequenceCount)*d == givenArray[i])
				{
					sequenceCount++;
					i++;
				}
				else
				{
					indexCount++;
					if(longestSequenceCount < sequenceCount)
					{
						longestSequenceCount = sequenceCount;
					}
					sequenceCount=0;
					i = indexCount;
				}
			}
			
			if(i == givenArray.length)
			{
				if(sequenceCount > longestSequenceCount)
					longestSequenceCount = sequenceCount;
			}
			
			
		}
		return longestSequenceCount;
	}
	
	
	public static void main(String[] args) {
		//-1 1 3 7 11 15 19 20 21 22 
		int[] givenNumber = new int[10];
		givenNumber[0] = -1;
		givenNumber[1] = 1;
		givenNumber[2] = 3;
		givenNumber[3] = 7;
		givenNumber[4] = 11;
		givenNumber[5] = 15;
		givenNumber[6] = 19;
		givenNumber[7] = 20;
		givenNumber[8] = 21;
		givenNumber[9] = 22;
		
		LargestArithmeticSequenceInGiveArray l = new LargestArithmeticSequenceInGiveArray();
		System.out.println(l.findLongestArithmeticSequence(givenNumber));
	}

}

public class LargestArithmeticSequenceInGiveArray {

int sequenceCount = 0;
int longestSequenceCount = 0;
int a_1 = 0;
int d = 0;

int indexCount = 0;
//a_n = a_1 + (n-1)d
public int findLongestArithmeticSequence(int[] givenArray)
{
if(givenArray.length <3)
{
return longestSequenceCount;
}

for(int i=0; i<givenArray.length;)
{
if(sequenceCount == 0)
{
a_1 = givenArray[i];
d = givenArray[i+1] - a_1;
sequenceCount++;
i++;
}
else if(sequenceCount>0)
{
if(a_1 + (sequenceCount)*d == givenArray[i])
{
sequenceCount++;
i++;
}
else
{
indexCount++;
if(longestSequenceCount < sequenceCount)
{
longestSequenceCount = sequenceCount;
}
sequenceCount=0;
i = indexCount;
}
}

if(i == givenArray.length)
{
if(sequenceCount > longestSequenceCount)
longestSequenceCount = sequenceCount;
}


}
return longestSequenceCount;
}


public static void main(String[] args) {
//-1 1 3 7 11 15 19 20 21 22
int[] givenNumber = new int[10];
givenNumber[0] = -1;
givenNumber[1] = 1;
givenNumber[2] = 3;
givenNumber[3] = 7;
givenNumber[4] = 11;
givenNumber[5] = 15;
givenNumber[6] = 19;
givenNumber[7] = 20;
givenNumber[8] = 21;
givenNumber[9] = 22;

LargestArithmeticSequenceInGiveArray l = new LargestArithmeticSequenceInGiveArray();
System.out.println(l.findLongestArithmeticSequence(givenNumber));
}

}