Regarding for nth term in Count and Say sequence.

11 février 2021 à 8:37:05

Hello Everyone, I am 1 year of experience in C++ and I have faced an interview on Facebook. The interviewer asked me, Can you explain how to find the nth term in Count and say sequence. Can anyone suggest me the syntax of this pattern or suggest me some tips for my upcoming second round of interview in Facebook.

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Edité par AnkitDixit 11 février 2021 à 8:41:54

ShalveeMeshram

16 février 2021 à 17:24:35

Here is the program:

#include <bits/stdc++.h>

using namespace std;

// Returns n'th term in look-and-say sequence

string countnndSay(int n)

{

// Base cases

if (n == 1) return "1";

if (n == 2) return "11";

// Find n'th term by generating all terms from 3 to

// n-1. Every term is generated using previous term

string str = "11"; // Initialize previous term

for (int i = 3; i<=n; i++)

{

// In below for loop, previous character

// is processed in current iteration. That

// is why a dummy character is added to make

// sure that loop runs one extra iteration.

str += '$';

int len = str.length();

int cnt = 1; // Initialize count of matching chars

string tmp = ""; // Initialize i'th term in series

// Process previous term to find the next term

for (int j = 1; j < len; j++)

{

// If current character does't match

if (str[j] != str[j-1])

{

// Append count of str[j-1] to temp

tmp += cnt + '0';

// Append str[j-1]

tmp += str[j-1];

// Reset count

cnt = 1;

}

// If matches, then increment count of matching

// characters

else cnt++;

}

// Update str

str = tmp;

}

return str;

}

// Driver program

int main()

{

int N = 3;

cout << countnndSay(N) << endl;

return 0;

}

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