array to zigzag fashion.cpp

/*
///////////////////////////////////////////
//Question/Info

Convert array into Zig-Zag fashion
Basic Accuracy: 58.96% Submissions: 7002 Points: 1
Given an array Arr (distinct elements) of size N. Rearrange the elements of array in zig-zag fashion. The converted array should be in form a < b > c < d > e < f. The relative order of elements is same in the output i.e you have to iterate on the original array only.

Example 1:

Input:
N = 7
Arr[] = {4, 3, 7, 8, 6, 2, 1}
Output: 3 7 4 8 2 6 1
Explanation: 3 < 7 > 4 < 8 > 2 < 6 > 1
Example 2:

Input:
N = 4
Arr[] = {1, 4, 3, 2}
Output: 1 4 2 3
Explanation: 1 < 4 > 2 < 3
Your Task:
You don't need to read input or print anything. Your task is to complete the function zigZag() which takes the array of integers arr and n as parameters and returns void. You need to modify the array itself.

Expected Time Complexity: O(N)
Expected Auxiliary Space: O(1)

Constraints:
1 <= N <= 105
0 <= Arri <= 106



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author: srj_v
///////////////////////////////////////////
*/

#include <bits/stdc++.h>
using namespace std;

// #define int 		   long long int
#define sbit(x) 	   __builtin_popcount(x)
#define pb(x) 		   push_back(x)
#define mp(x,y) 	   make_pair(x,y)
#define eb(x) 		   emplace_back(x)
#define ct(x) 		   cout << x << "\n";
#define ct2(x,y) 	   cout << x << " " << y << "\n";
#define tc(x) 		   cout << x << " ";
#define tc2(x,y) 	   cout << x << " " << y << " ";
#define forn(i,n) 	   for(int i = 0; i < (int)(n); ++i)
#define forx(i,x,n)    for(int i = x; i < (int)(n); ++i)
#define nfor(i,n)      for(int i = n-1; i >= 0; --i)
#define all(v) 		   v.begin(),v.end()
#define fsp(x,y)       fixed << setprecision(y) << x
#define PI 			   3.1415926535897932384626433832795
#define MOD 		   1000000007 // (1e9+7)
#define pii 		   pair<int,int>
#define pis 		   pair<int,string>
#define vi  		   vector<int>
#define vii 		   vector<pii>
#define mii 		   map<int,int>
#define p_q            priority_queue // priority_queue<int> (&) priority_queue< int,vi,greater<int> >
#define _IOS      	   ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

typedef long double ld;
typedef long long int lli;

#pragma GCC optimize("Ofast")

void c_p_c()
{
#ifndef ONLINE_JUDGE
	freopen("input.txt", "r", stdin);
	freopen("output.txt", "w", stdout);
#endif
}


int32_t main() {
///////////
	c_p_c();
///////////
	_IOS
//////////

	// code

	/*
	int t ; cin >> t; while(t--){}
	*/


	class Solution {
	public:
		// Program for zig-zag conversion of array
		void zigZag(int arr[], int n) {
			// code here

			// like wave sort

			for (int i = 0 ; i < n - 1 ; i++) {

				if (i & 1) {
					if (arr[i + 1] > arr[i]) {
						swap(arr[i + 1], arr[i]);
					}
				}

				else {
					if (arr[i] > arr[i + 1]) {
						swap(arr[i], arr[i + 1]);
					}
				}

			}

		}
	};




// cerr << "time: " << clock() << " ms" << '\n';
	return 0;
}