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stack using queue.cpp
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stack using queue.cpp
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/*
///////////////////////////////////////////
//Question/Info
Stack using two queues
Easy Accuracy: 40.49% Submissions: 56708 Points: 2
Implement a Stack using two queues q1 and q2.
Example 1:
Input:
push(2)
push(3)
pop()
push(4)
pop()
Output: 3 4
Explanation:
push(2) the stack will be {2}
push(3) the stack will be {2 3}
pop() poped element will be 3 the
stack will be {2}
push(4) the stack will be {2 4}
pop() poped element will be 4
Example 2:
Input:
push(2)
pop()
pop()
push(3)
Output: 2 -1
Your Task:
Since this is a function problem, you don't need to take inputs. You are required to complete the two methods push() which takes an integer 'x' as input denoting the element to be pushed into the stack and pop() which returns the integer poped out from the stack(-1 if the stack is empty).
Expected Time Complexity: O(1) for push() and O(N) for pop() (or vice-versa).
Expected Auxiliary Space: O(1) for both push() and pop().
Constraints:
1 <= Number of queries <= 100
1 <= values of the stack <= 100
Company Tags
Accolite Adobe Amazon Cisco CouponDunia D-E-Shaw Grofers Kritikal Solutions Oracle OYO Rooms Snapdeal Microsoft
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--){}
*/
/* The structure of the class is
class QueueStack{
private:
queue<int> q1;
queue<int> q2;
public:
void push(int);
int pop();
};
*/
//Function to push an element into stack using two queues.
void QueueStack :: push(int x)
{
// Your Code
q1.push(x);
}
//Function to pop an element from stack using two queues.
int QueueStack :: pop()
{
// Your Code
if (q1.empty()) {
return -1;
}
while (q1.size() != 1) {
q2.push(q1.front());
q1.pop();
}
int x = q1.front();
q1.pop();
while (!q2.empty()) {
q1.push(q2.front());
q2.pop();
}
return x;
}
// cerr << "time: " << clock() << " ms" << '\n';
return 0;
}