competitive-programming/solved-lightOj/1168.cpp at master · the-redback/competitive-programming · 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
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
/**
 *                                   ____
 *       ____ ___  ____ ________  __/ __/
 *      / __ `__ \/ __ `/ ___/ / / / /_
 *     / / / / / / /_/ / /  / /_/ / __/
 *    /_/ /_/ /_/\__,_/_/   \__,_/_/
 *
 *    @link : https://the-redback.com
 */
#include <bits/stdc++.h>
using namespace std;

#define mp        make_pair
#define pb(x)     push_back(x)
#define all(x)    x.begin(), x.end()
#define mem(a, b) memset(a, b, sizeof(a))
#define inf       1e9
#define eps       1e-9
#define NN        1050

bool wish[NN];
bool color[NN];
vector<int> arr;            // topological sorted node
vector<int> e[NN], ne[NN];  // Graph Before SCC
vector<int> te[NN];         // Transpose Graph Before SCC
vector<pair<int, int> > v;  // Edges Before SCC
map<pair<int, int>, int> mmp;
int id[NN];  // Id of Nodes After SCC
int in[NN], out[NN];

int dfs_1st(int u) {
    color[u] = true;
    for (int i = 0; i < e[u].size(); i++) {
        if (!color[e[u][i]]) dfs_1st(e[u][i]);
    }
    arr.pb(u);
}

int dfs_2nd(int u, int k) {
    color[u] = true;
    id[u] = k;

    for (int i = 0; i < te[u].size(); i++) {
        if (!color[te[u][i]]) dfs_2nd(te[u][i], k);
    }
}

string scc(int n) {
    arr.clear();
    mem(color, 0);
    int i, j, k, l;

    for (i = 0; i <= n; i++)
        if (color[i] == 0 && wish[i]) dfs_1st(i);

    reverse(all(arr));

    mem(id, -1);
    mem(color, 0);
    k = 0;

    for (i = 0; i < arr.size(); i++) {
        if (!color[arr[i]]) dfs_2nd(arr[i], k + 1), k++;
    }

    int node = k;

    mem(in, 0);
    mem(out, 0);

    int flag = 0;

    for (i = 0; i < v.size(); i++) {
        k = v[i].first;
        l = v[i].second;

        if (id[k] != id[l]) ne[id[k]].pb(id[l]), out[id[k]]++, in[id[l]]++, flag = 1;
    }
    int cnt = 0;
    if (out[id[0]] == 0 && flag) return "NO";
    for (i = 1; i <= node; i++) {
        if (in[i] != out[i]) {
            cnt++;
        }
        if (cnt > 2 || abs(in[i] - out[i]) >= 2) return "NO";
    }
    flag = 1;
    k = id[0];
    mem(color, 0);
    color[k] = true;
    while (flag) {
        flag = 0;
        for (i = 0; i < ne[k].size(); i++) {
            if (!color[ne[k][i]]) {
                color[ne[k][i]] = true;
                k = ne[k][i];
                flag = 1;
                break;
            }
        }
    }
    for (i = 0; i <= n; i++) {
        if (wish[i] && !color[id[i]]) return "NO";
    }

    return "YES";
}

int main() {
    ios_base::sync_with_stdio(false);
    int t = 1, tc;
    int i, j, k, l, m, n, man;

    cin >> tc;  // Test Case
    while (tc--) {
        cin >> n;  // n=node, m=edge
        int w;
        int mx = 0;
        mem(wish, 0);
        mmp.clear();
        for (i = 0; i < n; i++) {
            cin >> w;
            while (w--) {
                cin >> k >> l;
                if (mmp.find(mp(k, l)) == mmp.end()) {
                    e[k].pb(l);
                    te[l].pb(k);
                    v.pb(make_pair(k, l));
                    wish[k] = wish[l] = true;
                    mx = max(mx, k);
                    mx = max(mx, l);
                    mmp[mp(k, l)] = 1;
                }
            }
        }
        string sum = scc(mx);
        printf("Case %d: %s\n", t++, sum.c_str());
        for (i = 0; i <= mx; i++) {
            e[i].clear();
            te[i].clear();
            ne[i].clear();
        }
        v.clear();
    }
    return 0;
}