Coding_SkillSet_Topicwise/Answer73.cpp at main · BabesGotByte/Coding_SkillSet_Topicwise · 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
#include<bits/stdc++.h>
using namespace std;


class Solution
{
    private:
    bool knows(vector<vector<int> >& M, int a, int b, int n) {
        if(M[a][b] == 1)
            return true;
        else
            return false;
    }
    public:

    int celebrity(vector<vector<int> >& M, int n)
    {
        stack<int> s;
        //step1: push all element in stack
        for(int i=0; i<n; i++) {
            s.push(i);
        }


        while(s.size() > 1) {

            int a = s.top();
            s.pop();

            int b = s.top();
            s.pop();

            if(knows(M,a,b,n)){
                s.push(b);
            }
            else
            {
                s.push(a);
            }
        }
        int ans = s.top();

        int zeroCount = 0;

        for(int i=0; i<n; i++) {
            if(M[ans][i] == 0)
                zeroCount++;
        }

        //all zeroes
        if(zeroCount != n)
            return -1;

        //column check
        int oneCount = 0;

        for(int i=0; i<n; i++) {
            if(M[i][ans] == 1)
                oneCount++;
        }

        if(oneCount != n-1)
            return -1;

        return ans;

    }
};


int main()
{
    int t;
    cin>>t;
    while(t--)
    {
        int n;
        cin>>n;
        vector<vector<int> > M( n , vector<int> (n, 0));
        for(int i=0;i<n;i++)
        {
            for(int j=0;j<n;j++)
            {
                cin>>M[i][j];
            }
        }
        Solution ob;
        cout<<ob.celebrity(M,n)<<endl;

    }
}