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Submission #70729

# Submission time Handle Problem Language Result Execution time Memory
70729 2018-08-23T09:19:43 Z aquablitz11 Simurgh (IOI17_simurgh) C++14
100 / 100
 213 ms 30820 KB 
#include <bits/stdc++.h>
#include "simurgh.h"
using namespace std;
 
using pii = pair<int, int>;
#define F first
#define S second

const int N = 510;
const int M = N*(N-1)/2;
const int LIM = 30000;
 
int n, m;
vector<int> U, V; // edge list
vector<pii> G[N]; // adj list
vector<int> T; // tree edges
vector<pii> GT[N]; // tree adj list
bool is_tree[M];

int ans[M]; // answer to each edge (-1 = unknown)
int defcnt; // answer for the default spanning tree

int tick;
pii disc[N], low[N];
void dfs(int u, int p)
{
    disc[u] = low[u] = pii(++tick, -1);
    for (auto v : G[u]) {
        if (!disc[v.F].F) {
            // push edge to tree
            is_tree[v.S] = true;
            T.push_back(v.S);
            GT[u].emplace_back(v.F, v.S);
            GT[v.F].emplace_back(u, v.S);
            // tarjan's algorithm
            dfs(v.F, u);
            low[u] = min(low[u], low[v.F]);
            if (low[v.F].F > disc[u].F)
                ans[v.S] = 1;
        } else if (v.F != p) {
            low[u] = min(low[u], pii(disc[v.F].F, v.S));
        }
    }
}

vector<int> find_path(int u, int e, int t)
{
    if (u == t) {
        vector<int> ret;
        ret.push_back(e);
        return ret;
    }
    for (auto v : GT[u]) if (v.S != e) {
        vector<int> ret = find_path(v.F, v.S, t);
        if (!ret.empty()) {
            if (e != -1)
                ret.push_back(e);
            return ret;
        }
    }
    return vector<int>();
}

int get_changes(int rem, int add)
{
    vector<int> q(T);
    q.erase(find(q.begin(), q.end(), rem));
    q.push_back(add);
    return count_common_roads(q) - defcnt;
}

void query_cycle(int ce)
{
    if (ans[ce] != -1) return;
    int s = U[ce], t = V[ce];
    vector<int> path = find_path(s, -1, t);

    // find edge in path that we already know answer to
    int fnd = -1;
    for (auto e : path) {
        if (ans[e] != -1) {
            fnd = e;
            break;
        }
    }

    if (fnd != -1) { // case where we can quickly determine ce's value
        ans[ce] = ans[fnd] + get_changes(fnd, ce);
        for (auto e : path) { // update other edge in path we don't know
            if (ans[e] == -1)
                ans[e] = ans[ce] - get_changes(e, ce);
        }
    } else { // don't know, so query everything in the cycle
        for (auto e : path) {
            int d = get_changes(e, ce);
            if (d == 1)
                ans[ce] = 1, ans[e] = 0;
            else if (d == -1)
                ans[ce] = 0, ans[e] = 1;
        }
        if (ans[ce] == -1) ans[ce] = 0;
        for (auto e : path) {
            if (ans[e] == -1)
                ans[e] = ans[ce];
        }
    }
}

int par[N];
int root(int u) {
    if (par[u] == u) return u;
    return par[u] = root(par[u]);
}
bool merge(int u, int v) {
    u = root(u), v = root(v);
    if (u == v) return false;
    par[u] = v;
    return true;
}

int query_adj(vector<int> &adj)
{
    if (adj.empty()) return 0;
    iota(par, par+n, 0);
    vector<int> q;
    for (auto e : adj) {
        if (merge(U[e], V[e]))
            q.push_back(e);
    }
    int cnt = 0;
    for (auto e : T) {
        if (merge(U[e], V[e])) {
            cnt += ans[e];
            q.push_back(e);
        }
    }
    int ret = count_common_roads(q);
    return ret-cnt;
}

void solve(vector<int> &adj, int cnt = -1)
{
    if (cnt == -1)
        cnt = query_adj(adj);
    if (cnt == 0) {
        for (auto e : adj)
            ans[e] = 0;
        return;
    }
    if (cnt == adj.size()) {
        for (auto e : adj)
            ans[e] = 1;
        return;
    }

    int mid = adj.size()/2;
    vector<int> L(adj.begin(), adj.begin()+mid);
    vector<int> R(adj.begin()+mid, adj.end());
    int lcnt = query_adj(L);
    solve(L, lcnt);
    solve(R, cnt-lcnt);
}

vector<int> find_roads(int _n, vector<int> _U, vector<int> _V)
{
    // create adj list
    n = _n;
    U = _U, V = _V;
    m = U.size();
    for (int i = 0; i < m; ++i) {
        int u = U[i], v = V[i];
        G[u].emplace_back(v, i);
        G[v].emplace_back(u, i);
    }

    // build dfs tree and find answer for the tree
    fill(ans, ans+m, -1);
    dfs(0, -1);
    defcnt = count_common_roads(T);
    for (int i = 0; i < n; ++i) {
        if (low[i].S != -1)
            query_cycle(low[i].S);
    }

    // find answer for each node
    for (int u = 0; u < n; ++u) {
        vector<int> adj;
        for (auto v : G[u]) {
            if (ans[v.S] == -1)
                adj.push_back(v.S);
        }
        solve(adj);
    }

    // return answer
    vector<int> ret;
    for (int i = 0; i < m; ++i) {
        if (ans[i])
            ret.push_back(i);
    }
    return ret;
}

Compilation message

simurgh.cpp: In function 'void solve(std::vector<int>&, int)':
simurgh.cpp:150:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     if (cnt == adj.size()) {
         ~~~~^~~~~~~~~~~~~

Subtask #1
13.0 / 13.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 376 KB correct
2 Correct 4 ms 612 KB correct
3 Correct 3 ms 612 KB correct
4 Correct 3 ms 644 KB correct
5 Correct 2 ms 644 KB correct
6 Correct 3 ms 644 KB correct
7 Correct 3 ms 644 KB correct
8 Correct 2 ms 644 KB correct
9 Correct 4 ms 644 KB correct
10 Correct 2 ms 720 KB correct
11 Correct 4 ms 720 KB correct
12 Correct 3 ms 720 KB correct
13 Correct 3 ms 768 KB correct

Subtask #2
17.0 / 17.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 376 KB correct
2 Correct 4 ms 612 KB correct
3 Correct 3 ms 612 KB correct
4 Correct 3 ms 644 KB correct
5 Correct 2 ms 644 KB correct
6 Correct 3 ms 644 KB correct
7 Correct 3 ms 644 KB correct
8 Correct 2 ms 644 KB correct
9 Correct 4 ms 644 KB correct
10 Correct 2 ms 720 KB correct
11 Correct 4 ms 720 KB correct
12 Correct 3 ms 720 KB correct
13 Correct 3 ms 768 KB correct
14 Correct 5 ms 768 KB correct
15 Correct 5 ms 768 KB correct
16 Correct 5 ms 768 KB correct
17 Correct 5 ms 768 KB correct
18 Correct 3 ms 768 KB correct
19 Correct 4 ms 768 KB correct
20 Correct 4 ms 768 KB correct
21 Correct 5 ms 768 KB correct
22 Correct 4 ms 816 KB correct
23 Correct 4 ms 816 KB correct
24 Correct 4 ms 816 KB correct
25 Correct 3 ms 816 KB correct
26 Correct 4 ms 816 KB correct
27 Correct 4 ms 816 KB correct
28 Correct 4 ms 816 KB correct
29 Correct 4 ms 816 KB correct
30 Correct 4 ms 816 KB correct
31 Correct 4 ms 816 KB correct
32 Correct 4 ms 816 KB correct
33 Correct 4 ms 816 KB correct

Subtask #3
21.0 / 21.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 376 KB correct
2 Correct 4 ms 612 KB correct
3 Correct 3 ms 612 KB correct
4 Correct 3 ms 644 KB correct
5 Correct 2 ms 644 KB correct
6 Correct 3 ms 644 KB correct
7 Correct 3 ms 644 KB correct
8 Correct 2 ms 644 KB correct
9 Correct 4 ms 644 KB correct
10 Correct 2 ms 720 KB correct
11 Correct 4 ms 720 KB correct
12 Correct 3 ms 720 KB correct
13 Correct 3 ms 768 KB correct
14 Correct 5 ms 768 KB correct
15 Correct 5 ms 768 KB correct
16 Correct 5 ms 768 KB correct
17 Correct 5 ms 768 KB correct
18 Correct 3 ms 768 KB correct
19 Correct 4 ms 768 KB correct
20 Correct 4 ms 768 KB correct
21 Correct 5 ms 768 KB correct
22 Correct 4 ms 816 KB correct
23 Correct 4 ms 816 KB correct
24 Correct 4 ms 816 KB correct
25 Correct 3 ms 816 KB correct
26 Correct 4 ms 816 KB correct
27 Correct 4 ms 816 KB correct
28 Correct 4 ms 816 KB correct
29 Correct 4 ms 816 KB correct
30 Correct 4 ms 816 KB correct
31 Correct 4 ms 816 KB correct
32 Correct 4 ms 816 KB correct
33 Correct 4 ms 816 KB correct
34 Correct 35 ms 2316 KB correct
35 Correct 35 ms 2472 KB correct
36 Correct 32 ms 2472 KB correct
37 Correct 11 ms 2472 KB correct
38 Correct 34 ms 2860 KB correct
39 Correct 45 ms 2932 KB correct
40 Correct 26 ms 2932 KB correct
41 Correct 34 ms 3368 KB correct
42 Correct 35 ms 3568 KB correct
43 Correct 16 ms 3568 KB correct
44 Correct 22 ms 3568 KB correct
45 Correct 16 ms 3568 KB correct
46 Correct 16 ms 3568 KB correct
47 Correct 11 ms 3568 KB correct
48 Correct 5 ms 3568 KB correct
49 Correct 6 ms 3568 KB correct
50 Correct 14 ms 3568 KB correct
51 Correct 17 ms 3568 KB correct
52 Correct 15 ms 3568 KB correct
53 Correct 14 ms 3568 KB correct
54 Correct 18 ms 3996 KB correct
55 Correct 15 ms 3996 KB correct
56 Correct 18 ms 3996 KB correct
57 Correct 17 ms 4056 KB correct

Subtask #4
19.0 / 19.0

# Verdict Execution time Memory Grader output
1 Correct 2 ms 4056 KB correct
2 Correct 3 ms 4056 KB correct
3 Correct 93 ms 7848 KB correct
4 Correct 140 ms 10608 KB correct
5 Correct 213 ms 11504 KB correct
6 Correct 135 ms 12432 KB correct
7 Correct 104 ms 13320 KB correct
8 Correct 133 ms 14288 KB correct
9 Correct 150 ms 15216 KB correct
10 Correct 161 ms 16236 KB correct
11 Correct 161 ms 17096 KB correct
12 Correct 153 ms 18000 KB correct
13 Correct 2 ms 18000 KB correct
14 Correct 167 ms 18820 KB correct
15 Correct 161 ms 19860 KB correct

Subtask #5
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 376 KB correct
2 Correct 4 ms 612 KB correct
3 Correct 3 ms 612 KB correct
4 Correct 3 ms 644 KB correct
5 Correct 2 ms 644 KB correct
6 Correct 3 ms 644 KB correct
7 Correct 3 ms 644 KB correct
8 Correct 2 ms 644 KB correct
9 Correct 4 ms 644 KB correct
10 Correct 2 ms 720 KB correct
11 Correct 4 ms 720 KB correct
12 Correct 3 ms 720 KB correct
13 Correct 3 ms 768 KB correct
14 Correct 5 ms 768 KB correct
15 Correct 5 ms 768 KB correct
16 Correct 5 ms 768 KB correct
17 Correct 5 ms 768 KB correct
18 Correct 3 ms 768 KB correct
19 Correct 4 ms 768 KB correct
20 Correct 4 ms 768 KB correct
21 Correct 5 ms 768 KB correct
22 Correct 4 ms 816 KB correct
23 Correct 4 ms 816 KB correct
24 Correct 4 ms 816 KB correct
25 Correct 3 ms 816 KB correct
26 Correct 4 ms 816 KB correct
27 Correct 4 ms 816 KB correct
28 Correct 4 ms 816 KB correct
29 Correct 4 ms 816 KB correct
30 Correct 4 ms 816 KB correct
31 Correct 4 ms 816 KB correct
32 Correct 4 ms 816 KB correct
33 Correct 4 ms 816 KB correct
34 Correct 35 ms 2316 KB correct
35 Correct 35 ms 2472 KB correct
36 Correct 32 ms 2472 KB correct
37 Correct 11 ms 2472 KB correct
38 Correct 34 ms 2860 KB correct
39 Correct 45 ms 2932 KB correct
40 Correct 26 ms 2932 KB correct
41 Correct 34 ms 3368 KB correct
42 Correct 35 ms 3568 KB correct
43 Correct 16 ms 3568 KB correct
44 Correct 22 ms 3568 KB correct
45 Correct 16 ms 3568 KB correct
46 Correct 16 ms 3568 KB correct
47 Correct 11 ms 3568 KB correct
48 Correct 5 ms 3568 KB correct
49 Correct 6 ms 3568 KB correct
50 Correct 14 ms 3568 KB correct
51 Correct 17 ms 3568 KB correct
52 Correct 15 ms 3568 KB correct
53 Correct 14 ms 3568 KB correct
54 Correct 18 ms 3996 KB correct
55 Correct 15 ms 3996 KB correct
56 Correct 18 ms 3996 KB correct
57 Correct 17 ms 4056 KB correct
58 Correct 2 ms 4056 KB correct
59 Correct 3 ms 4056 KB correct
60 Correct 93 ms 7848 KB correct
61 Correct 140 ms 10608 KB correct
62 Correct 213 ms 11504 KB correct
63 Correct 135 ms 12432 KB correct
64 Correct 104 ms 13320 KB correct
65 Correct 133 ms 14288 KB correct
66 Correct 150 ms 15216 KB correct
67 Correct 161 ms 16236 KB correct
68 Correct 161 ms 17096 KB correct
69 Correct 153 ms 18000 KB correct
70 Correct 2 ms 18000 KB correct
71 Correct 167 ms 18820 KB correct
72 Correct 161 ms 19860 KB correct
73 Correct 2 ms 19860 KB correct
74 Correct 184 ms 20760 KB correct
75 Correct 140 ms 21520 KB correct
76 Correct 83 ms 21520 KB correct
77 Correct 146 ms 22884 KB correct
78 Correct 165 ms 23740 KB correct
79 Correct 170 ms 24676 KB correct
80 Correct 163 ms 25600 KB correct
81 Correct 117 ms 25744 KB correct
82 Correct 167 ms 27128 KB correct
83 Correct 114 ms 27128 KB correct
84 Correct 72 ms 27128 KB correct
85 Correct 61 ms 27128 KB correct
86 Correct 56 ms 27128 KB correct
87 Correct 47 ms 27128 KB correct
88 Correct 35 ms 27128 KB correct
89 Correct 42 ms 27128 KB correct
90 Correct 36 ms 27128 KB correct
91 Correct 24 ms 27128 KB correct
92 Correct 10 ms 27128 KB correct
93 Correct 81 ms 28296 KB correct
94 Correct 48 ms 28296 KB correct
95 Correct 48 ms 28296 KB correct
96 Correct 34 ms 28296 KB correct
97 Correct 35 ms 28296 KB correct
98 Correct 38 ms 28296 KB correct
99 Correct 38 ms 28296 KB correct
100 Correct 25 ms 28296 KB correct
101 Correct 12 ms 28296 KB correct
102 Correct 67 ms 29456 KB correct
103 Correct 65 ms 29920 KB correct
104 Correct 60 ms 30416 KB correct
105 Correct 61 ms 30820 KB correct