Leetcode75/Matchsticks_Square.cpp at main · kasakvaish/Leetcode75 · 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
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;
#define ff                 first
#define ss                 second
#define endl               "\n"
#define ll                 long long
#define ld                 long double
#define loop(a, b, c)      for(ll (a) = (b); (a)<=(c); (a)++)
#define looprev(a, b, c)   for(ll (a) = (b); (a)>=(c); (a)--)
#define pb                 push_back
#define mp                 make_pair
#define pii                pair<ll, ll>
#define vi                 vector<ll>
#define mii                map<ll, ll>
#define pqb                priority_queue<ll>
#define pqs                priority_queue<int, vi, greater<ll> >
#define setbits(x)         __builtin_popcountll(x)
#define zrobits(x)         __builtin_ctzll(x)
#define mod                1000000007
#define inf                1e18
#define ps(x, y)           fixed<<setprecision(y)<<x
#define mk(arr,n,type)     type *arr = new type[n];
#define w(t)               int x; cin>>x; while(x--)
// mt19937                    rng(chrono::steady_clock::now,time_since_epoch(),count());
typedef tree<pair<int, int>, null_type, less<pair<int, int>>, rb_tree_tag, tree_order_statistics_node_update> pbds;


void file_i_o(){
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	/* #ifndef ONLINE_JUDGE
		freopen("input.txt", "r", stdin);
		freopen("output.txt", "w", stdout);
	#endif */
}


class Solution {
public:

	bool dfs(vector<int>& matchsticks, int target, vector<int>&sides, int idx){
		// Base Case
		if(idx == matchsticks.size()){
			if(sides[0] == sides[1] and sides[1] == sides[2] and sides[2] == sides[3])
				return true;
			return false;
		}

		for(int i = 0; i < 4; i++){
			if(sides[i] + matchsticks[idx] > target) //Optimization 1
				continue;

			int j = i-1;
			while(j >= 0){ // Optimization 3
				if(sides[j] == sides[i]){
					break;
				}

				j--;
			}

			if(j != -1)
				continue;

			sides[i] += matchsticks[idx];
			if(dfs(matchsticks, target, sides, idx + 1))
				return true;
			sides[i] -= matchsticks[idx]; //backtrack
		}
		return false;
	}

    bool makesquare(vector<int>& matchsticks) {
    	// Edge Case
    	if(matchsticks.size() == 0)
    		return false;

    	int sum = 0;
    	for(int i = 0; i < matchsticks.size(); i++){
    		sum += matchsticks[i];
    	}

    	int target = sum / 4;

    	vector<int> sides(4, 0);

    	sort(matchsticks.begin(), matchsticks.end(), greater<int>()); // Optimization 2

    	return dfs(matchsticks, target, sides, 0);
    }
};

int main(int argc, char const *argv[])
{

	file_i_o();

	clock_t start, end;
    start = clock();

	int n;
	cin >> n;

	vector<int> matches(n);

	loop(i, 0, n){
		cin >> matches[i];
	}

	Solution mksqr = makesquare(matches);

	if(mksqr)
		cout << "TRUE"<< endl;
	else
		cout << "FALSE" << endl;

	end = clock();

	double time_taken=double(end-start)/double(CLOCKS_PER_SEC);
    cerr<<"\nTime : "<<fixed<<time_taken<<setprecision(5)<<" s \n";
    cerr<<"\n" << "Coded By S!r Black-D3vil" <<"\n";

	return 0;
}