Palindrome

Description:

In the beginning of the new year Keivan decided to reverse his name. He doesn't like palindromes, so he changed Naviek to Navick. He is too selfish, so for a given n he wants to obtain a string of n characters, each of which is either 'a', 'b' or 'c', with no palindromes of length 3 appearing in the string as a substring. For example, the strings "abc" and "abca" suit him, while the string "aba" doesn't. He also want the number of letters 'c' in his string to be as little as possible. Input The first line contains single integer n (1<=n<=2 10 power 5) the length of the string. Output Print the string that satisfies all the constraints. If there are multiple answers, print any of them. Test Case 1 Input (stdin) 2 Expected Output bb Test Case 2 Input (stdin) 3 Expected Output bbasolution

Program :

#include <set>
#include <list>
#include <map>
#include <ratio>
#include <stack>
#include <regex>
#include <ctime>
#include <string>
#include <cmath>
#include <queue>
#include <cstdio>
#include <vector>
#include <cctype>
#include <climits>
#include <cstring>
#include <cstdlib>
#include <sstream>
#include <numeric>
#include <iostream>
#include <complex>
#include <algorithm>
#include <functional>
#include <unordered_set>
#include <unordered_map>
#define ms(a) memset(a,0,sizeof(a))
#define rep(a,v,b) for(int a=v;a<b;a++)
#define repe(a,v,b) for(int a=v;a<=b;a++)
#define tp(_pair_or_tuple,_index) get<_index>(_pair_or_tuple)
typedef long long LL;
const LL LINF = LLONG_MAX;
const int INF = INT_MAX;
const int MAXN = 2e5 + 10;
const int MOD = 1e9 + 7;
const double eps = 1e-7;
const double PI = acos(-1.0);
using namespace std;
template <typename T>
T GCD(T a, T b)
{
 if (!b)return a;
 return GCD(b, a%b);
}
template <typename T>
T LCM(T a, T b)
{
 return a*b / GCD(a, b);
}

int main()
{
 int n; cin >> n;
 string s;
 bool f = false;
 for (int i = 0; i < n / 2; i++)
 {
  s += (f ? "aa" : "bb");
  f = !f;
 }
 if (n % 2)s += (!f ? "b" : "a");
 cout << s << endl;
 return 0;
}