Algorithm-Snippets/minqueue.cpp at master · ankeetparikh/Algorithm-Snippets · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
#include <bits/stdc++.h>
#define pb push_back

typedef long long ll;
typedef long double ld;

using namespace std;

/*
	normal queue with the following operations:
	s.min()
	s.push(int x)
	s.pop()
	s.front()
	s.back()
	s.empty()
	s.size()
*/

struct min_queue{
	vector<pair<ll, ll>> a, b;

	int size(){
		return a.size() + b.size();
	}

	bool empty(){
		return a.empty() && b.empty();
	}

	void clear(){
		a.clear(); b.clear();
	}

	ll min_element() const {
		ll v = 3e18;
		if(b.size()) v = min(v, b.back().second);
		if(a.size()) v = min(v, a.back().second);
		return v;
	}

	void push(ll x){
		a.push_back({x, a.empty() ? x : min(x, a.back().second)});
	}

	void pop(){
		if(empty()) return;
		if(b.empty()) transfer();
		b.pop_back();
	}

	int front(){
		if(b.empty()) transfer();
		return b.back().first;
	}

	int back(){
		return a.size() ? a.back().first : b.front().first;
	}

	void transfer(){
		if(!b.empty()) return;
		while(!a.empty()){
			ll x = a.back().first;
			a.pop_back();
			b.push_back({x, b.empty() ? x : min(x, b.back().second)});
		}
	}
};


struct max_queue{
	vector<pair<ll, ll>> a, b;

	int size(){
		return a.size() + b.size();
	}

	bool empty(){
		return a.empty() && b.empty();
	}

	void clear(){
		a.clear(); b.clear();
	}

	ll max_element() {
		ll v = -3e18;
		if(b.size()) v = max(v, b.back().second);
		if(a.size()) v = max(v, a.back().second);
		return v;
	}

	void push(ll x){
		a.push_back({x, a.empty() ? x : max(x, a.back().second)});
	}

	void pop(){
		if(empty()) return;
		if(b.empty()) transfer();
		b.pop_back();
	}

	int front(){
		if(b.empty()) transfer();
		return b.back().first;
	}

	int back(){
		return a.size() ? a.back().first : b.front().first;
	}

	void transfer(){
		if(!b.empty()) return;
		while(!a.empty()){
			ll x = a.back().first;
			a.pop_back();
			b.push_back({x, b.empty() ? x : max(x, b.back().second)});
		}
	}
};

int main(){
	min_queue m;
	m.push(1); m.push(2); m.push(3);
	m.pop();
	cout << m.min_element() << endl;
	m.pop();
	cout << m.min_element() << endl;
}