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Submission #932926

# Submission time Handle Problem Language Result Execution time Memory
932926 2024-02-24T14:42:48 Z asdasdqwer Love Polygon (BOI18_polygon) C++14
100 / 100
 289 ms 27732 KB 
#include <bits/stdc++.h>
using namespace std;

#define int int64_t

signed main() {
    int n;cin>>n;
    
    if (n % 2 != 0) {
        cout<<-1<<"\n";
        return 0;
    }

    map<string,int> mp;
    vector<vector<int>> in(n);
    vector<int> out(n);
    int cnt=0;
    for (int i=0;i<n;i++) {
        string s1, s2;cin>>s1>>s2;
        if (mp.find(s1) == mp.end()) {
            mp[s1] = cnt++;
        }

        if (mp.find(s2) == mp.end()) {
            mp[s2] = cnt++;
        }
        if (mp[s1] != mp[s2])
            in[mp[s2]].push_back(mp[s1]);
        out[mp[s1]] = mp[s2];
    }

    // remove all relationships (cycles of length 2)
    int swaps = n;
    vector<bool> vis1(n, false);

    for (int i=0;i<n;i++) {
        if (vis1[i])continue;
        if (out[out[i]] != i || out[i] == i) continue;
        vis1[i] = true;
        vis1[out[i]] = true;
        for (auto &x:in[i]) {
            out[x] = x;
        }

        for (auto &x:in[out[i]]) {
            out[x] = x;
        }

        swaps -= 2;
    }

    // get rid of all cycles of length 1 (people that love themselves), and the respective lines connected to them
    vector<int> dpWith(n, 0), dpWithout(n, 0);
    function<void(int)> dfs1=[&](int node) {
        vis1[node] = true;
        int sm = 0;
        for (auto &x:in[node]) {
            dfs1(x);
            dpWithout[node] += max(dpWith[x], dpWithout[x]);
            sm += max(dpWith[x], dpWithout[x]);
        }

        for (auto &x:in[node]) {
            dpWith[node] = max(dpWith[node], sm - max(dpWith[x], dpWithout[x]) + dpWithout[x] + 1);
        }
    };

    for (int i=0;i<n;i++) {
        if (out[i] == i && !vis1[i]) {
            dfs1(i);
            swaps -= max(dpWith[i], dpWithout[i]);
        }
    }

    // find all nodes that are part of a cycle
    vector<bool> incycle(n, false);
    vector<int> stat(n, 0);
    vector<bool> vis = vis1;

    function<int(int)> dfs2=[&](int node) -> int {
        vis[node] = true;
        // still being processed
        stat[node] = 1;
        if (stat[out[node]] == 0) {
            int d = dfs2(out[node]);
            if (d != -1) {
                incycle[node] = true;
            }

            if (d == node) {
                d = -1;
            }
            stat[node] = 2;
            return d;
        }

        else if (stat[out[node]] == 1) {
            stat[node] = 2;
            incycle[node] = true;
            return out[node];
        }

        // finished processing
        stat[node] = 2;
        return -1;
    };

    for (int i=0;i<n;i++) {
        if (!vis[i]) dfs2(i);
    }

    // calculate dp values for all nodes in a cycle
    function<void(int)> dfs3=[&](int node) {
        int sm = 0;
        for (auto &x:in[node]) {
            if (incycle[x])continue;
            dfs3(x);
            dpWithout[node] += max(dpWith[x], dpWithout[x]);
            sm += max(dpWith[x], dpWithout[x]);
        }

        for (auto &x:in[node]) {
            if (incycle[x])continue;
            dpWith[node] = max(dpWith[node], sm - max(dpWith[x], dpWithout[x]) + dpWithout[x] + 1);
        }
    };

    for (int i=0;i<n;i++) {
        if (incycle[i]) {
            dfs3(i);
            swaps -= dpWith[i];
        }
    }

    vis.clear();
    vis.assign(n, false);

    for (int i=0;i<n;i++) {
        if (incycle[i] && !vis[i]) {
            int pt = i;
            vector<bool> pos;
            do {
                pos.push_back(dpWith[pt] == dpWithout[pt]);
                vis[pt] = true;
                pt = out[pt];
            } while (pt != i);
            
            vector<bool> tmp;
            while (pos.size() && pos.back() == true) {
                tmp.push_back(true);
                pos.pop_back();
            }

            for (bool x:pos) {
                tmp.push_back(x);
            }
            tmp.push_back(false);

            stack<bool> st;
            for (bool x:tmp) {
                if (x) {
                    st.push(x);
                }

                else {
                    swaps -= ((int)st.size() / 2);
                    while (st.size()) st.pop();
                }
            }
        }
    }

    cout<<swaps<<"\n";
}

Subtask #1
21.0 / 21.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 344 KB Output is correct
2 Correct 0 ms 348 KB Output is correct
3 Correct 0 ms 348 KB Output is correct
4 Correct 0 ms 348 KB Output is correct
5 Correct 0 ms 348 KB Output is correct
6 Correct 0 ms 348 KB Output is correct
7 Correct 1 ms 348 KB Output is correct
8 Correct 0 ms 348 KB Output is correct
9 Correct 0 ms 348 KB Output is correct
10 Correct 0 ms 348 KB Output is correct
11 Correct 0 ms 348 KB Output is correct
12 Correct 1 ms 348 KB Output is correct
13 Correct 0 ms 348 KB Output is correct
14 Correct 1 ms 348 KB Output is correct
15 Correct 1 ms 348 KB Output is correct

Subtask #2
25.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 348 KB Output is correct
2 Correct 0 ms 600 KB Output is correct
3 Correct 0 ms 348 KB Output is correct
4 Correct 257 ms 24396 KB Output is correct
5 Correct 260 ms 19000 KB Output is correct
6 Correct 289 ms 25324 KB Output is correct
7 Correct 0 ms 444 KB Output is correct

Subtask #3
29.0 / 29.0

# Verdict Execution time Memory Grader output
1 Correct 276 ms 18688 KB Output is correct
2 Correct 260 ms 20564 KB Output is correct
3 Correct 190 ms 15716 KB Output is correct
4 Correct 0 ms 344 KB Output is correct
5 Correct 267 ms 27732 KB Output is correct
6 Correct 249 ms 17672 KB Output is correct
7 Correct 253 ms 17672 KB Output is correct
8 Correct 228 ms 17148 KB Output is correct
9 Correct 234 ms 17292 KB Output is correct
10 Correct 188 ms 16896 KB Output is correct
11 Correct 0 ms 348 KB Output is correct
12 Correct 0 ms 348 KB Output is correct
13 Correct 0 ms 348 KB Output is correct
14 Correct 0 ms 348 KB Output is correct

Subtask #4
25.0 / 25.0

# Verdict Execution time Memory Grader output
1 Correct 1 ms 344 KB Output is correct
2 Correct 0 ms 348 KB Output is correct
3 Correct 0 ms 348 KB Output is correct
4 Correct 0 ms 348 KB Output is correct
5 Correct 0 ms 348 KB Output is correct
6 Correct 0 ms 348 KB Output is correct
7 Correct 1 ms 348 KB Output is correct
8 Correct 0 ms 348 KB Output is correct
9 Correct 0 ms 348 KB Output is correct
10 Correct 0 ms 348 KB Output is correct
11 Correct 0 ms 348 KB Output is correct
12 Correct 1 ms 348 KB Output is correct
13 Correct 0 ms 348 KB Output is correct
14 Correct 1 ms 348 KB Output is correct
15 Correct 1 ms 348 KB Output is correct
16 Correct 1 ms 348 KB Output is correct
17 Correct 0 ms 600 KB Output is correct
18 Correct 0 ms 348 KB Output is correct
19 Correct 257 ms 24396 KB Output is correct
20 Correct 260 ms 19000 KB Output is correct
21 Correct 289 ms 25324 KB Output is correct
22 Correct 0 ms 444 KB Output is correct
23 Correct 276 ms 18688 KB Output is correct
24 Correct 260 ms 20564 KB Output is correct
25 Correct 190 ms 15716 KB Output is correct
26 Correct 0 ms 344 KB Output is correct
27 Correct 267 ms 27732 KB Output is correct
28 Correct 249 ms 17672 KB Output is correct
29 Correct 253 ms 17672 KB Output is correct
30 Correct 228 ms 17148 KB Output is correct
31 Correct 234 ms 17292 KB Output is correct
32 Correct 188 ms 16896 KB Output is correct
33 Correct 0 ms 348 KB Output is correct
34 Correct 0 ms 348 KB Output is correct
35 Correct 0 ms 348 KB Output is correct
36 Correct 0 ms 348 KB Output is correct
37 Correct 266 ms 18772 KB Output is correct
38 Correct 254 ms 18768 KB Output is correct
39 Correct 268 ms 17656 KB Output is correct
40 Correct 263 ms 17856 KB Output is correct
41 Correct 252 ms 17748 KB Output is correct
42 Correct 256 ms 18000 KB Output is correct
43 Correct 256 ms 17924 KB Output is correct
44 Correct 257 ms 17996 KB Output is correct
45 Correct 270 ms 18076 KB Output is correct
46 Correct 256 ms 18060 KB Output is correct
47 Correct 239 ms 17492 KB Output is correct
48 Correct 258 ms 18488 KB Output is correct
49 Correct 271 ms 20564 KB Output is correct
50 Correct 190 ms 15784 KB Output is correct
51 Correct 0 ms 348 KB Output is correct
52 Correct 274 ms 27524 KB Output is correct
53 Correct 247 ms 17560 KB Output is correct
54 Correct 267 ms 17796 KB Output is correct
55 Correct 223 ms 16888 KB Output is correct
56 Correct 236 ms 17236 KB Output is correct
57 Correct 192 ms 16672 KB Output is correct
58 Correct 0 ms 348 KB Output is correct
59 Correct 0 ms 348 KB Output is correct
60 Correct 0 ms 348 KB Output is correct
61 Correct 0 ms 348 KB Output is correct
62 Correct 0 ms 348 KB Output is correct
63 Correct 0 ms 348 KB Output is correct
64 Correct 0 ms 348 KB Output is correct
65 Correct 257 ms 24456 KB Output is correct
66 Correct 275 ms 18844 KB Output is correct
67 Correct 256 ms 25424 KB Output is correct
68 Correct 0 ms 348 KB Output is correct
69 Correct 0 ms 348 KB Output is correct
70 Correct 0 ms 348 KB Output is correct
71 Correct 1 ms 348 KB Output is correct
72 Correct 0 ms 348 KB Output is correct
73 Correct 0 ms 344 KB Output is correct
74 Correct 0 ms 348 KB Output is correct
75 Correct 0 ms 348 KB Output is correct
76 Correct 0 ms 348 KB Output is correct
77 Correct 0 ms 348 KB Output is correct
78 Correct 1 ms 344 KB Output is correct
79 Correct 0 ms 348 KB Output is correct
80 Correct 0 ms 348 KB Output is correct
81 Correct 0 ms 348 KB Output is correct
82 Correct 0 ms 348 KB Output is correct
83 Correct 0 ms 348 KB Output is correct