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Submission #88717

# Submission time Handle Problem Language Result Execution time Memory
88717 2018-12-07T18:43:19 Z popovicirobert Pipes (BOI13_pipes) C++14
100 / 100
 288 ms 22548 KB 
#include <bits/stdc++.h>
#define lsb(x) (x & (-x))
#define ll long long
#define ull unsigned long long
// 217
// 44

using namespace std;

const int MAXM = (int) 5e5;
const int MAXN = (int) 1e5;

vector < pair <int, int> > g[MAXN + 1];
int even[MAXN + 1], father[MAXN + 1], n;
bool vis[MAXN + 1];

void dfs(int nod) {
    vis[nod] = 1;
    for(auto it : g[nod]) {
        if(vis[it.first] == 0) {
            even[it.first] = (even[nod] ^ 1);
            father[it.first] = nod;
            dfs(it.first);
        }
    }
}

inline void detect_cycle(bool &cycle) {
    memset(even, -1, sizeof(even));
    even[1] = 0;
    dfs(1);
    int cnt = 0;
    for(int i = 1; i <= n; i++) {
        for(auto it : g[i]) {
            if(even[i] != even[it.first] && !(father[it.first] == i || father[i] == it.first)) {
                cout << 0;
                exit(0);
            }
            if(even[i] == even[it.first]) {
                cnt++;
            }
        }
    }
    cnt /= 2;
    if(cnt > 1) {
        cout << 0;
        exit(0);
    }
    if(cnt) {
        cycle = 1;
    }
}

ll c[MAXN + 1];
ll sol[MAXM + 1];

int deg[MAXN + 1];

inline void solve_tree(bool cycle) {
    int i;
    memset(father, 0, sizeof(father));
    memset(vis, 0, sizeof(vis));
    queue <int> Q;
    for(i = 1; i <= n; i++) {
        if(g[i].size() == 1) {
            Q.push(i);
            vis[i] = 1;
        }
    }
    int root;
    while(Q.size()) {
        int nod = Q.front();
        root = nod;
        Q.pop();
        for(auto it : g[nod]) {
            if(father[it.first] != nod) {
                deg[it.first]++;
                father[nod] = it.first;
                sol[it.second] = c[nod];
                c[it.first] -= c[nod];
                c[nod] = 0;
                if(deg[it.first] + 1 == g[it.first].size()) {
                    Q.push(it.first);
                    vis[it.first] = 1;
                }
            }
        }
    }
    if(cycle == 0) {
        for(i = 1; i <= n; i++) {
            if(c[i] != 0) {
                cout << 0;
                exit(0);
            }
        }
    }
}

void dfs1(int nod, vector < pair <int, int> > &nodes, int par, int root) {
    vis[nod] = 1;
    for(auto it : g[nod]) {
        if(it.first == par) {
            continue;
        }
        if(vis[it.first] == 0) {
            nodes.push_back({nod, it.second});
            dfs1(it.first, nodes, nod, root);
        }
        else if(it.first == root) {
            nodes.push_back({nod, it.second});
        }
    }
}

inline void solve_cycle(bool cycle) {
    if(cycle == 0) {
        return ;
    }
    int i, nod;
    for(i = 1; i <= n; i++) {
        if(vis[i] == 0) {
            nod = i;
            break;
        }
    }
    vector < pair <int, int> > nodes;
    dfs1(nod, nodes, 0, nod);
    int sz = nodes.size();
    ll tot = 0;
    for(auto it : nodes) {
        tot += c[it.first];
    }
    tot /= 2;
    ll sum = 0;
    for(i = 0; i + 1 < sz; i += 2) {
        sum += c[nodes[i].first];
    }
    sol[nodes[sz - 2].second] = tot - sum;
    c[nodes[sz - 2].first] -= tot - sum;
    for(i = sz - 3; i >= 0; i--) {
        sol[nodes[i].second] = c[nodes[i + 1].first];
        c[nodes[i].first] -= sol[nodes[i].second];
    }
    sum = 0;
    for(auto it : nodes) {
        sum += sol[it.second];
    }
    sol[nodes.back().second] = tot - sum;
}

int main() {
    //ifstream cin("A.in");
    //ofstream cout("A.out");
    int i, m;
    ios::sync_with_stdio(false);
    cin.tie(0), cout.tie(0);
    cin >> n >> m;
    for(i = 1; i <= n; i++) {
        cin >> c[i];
        c[i] *= 2LL;
    }
    for(i = 1; i <= m; i++) {
        int x, y;
        cin >> x >> y;
        g[x].push_back({y, i});
        g[y].push_back({x, i});
    }
    bool cycle = 0;
    detect_cycle(cycle);
    solve_tree(cycle);
    solve_cycle(cycle);
    for(i = 1; i <= m; i++) {
        cout << sol[i] << "\n";
    }
    //cin.close();
    //cout.close();
    return 0;
}

Compilation message

pipes.cpp: In function 'void solve_tree(bool)':
pipes.cpp:82:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
                 if(deg[it.first] + 1 == g[it.first].size()) {
                    ~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~
pipes.cpp:70:9: warning: variable 'root' set but not used [-Wunused-but-set-variable]
     int root;
         ^~~~
pipes.cpp: In function 'void solve_cycle(bool)':
pipes.cpp:127:9: warning: 'nod' may be used uninitialized in this function [-Wmaybe-uninitialized]
     dfs1(nod, nodes, 0, nod);
     ~~~~^~~~~~~~~~~~~~~~~~~~

Subtask #1
30.0 / 30.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 3580 KB Output is correct
2 Correct 4 ms 3708 KB Output is correct
3 Correct 5 ms 3784 KB Output is correct
4 Correct 93 ms 10108 KB Output is correct
5 Correct 5 ms 10108 KB Output is correct
6 Correct 4 ms 10108 KB Output is correct
7 Correct 4 ms 10108 KB Output is correct
8 Correct 5 ms 10108 KB Output is correct
9 Correct 5 ms 10108 KB Output is correct
10 Correct 5 ms 10108 KB Output is correct
11 Correct 5 ms 10108 KB Output is correct
12 Correct 5 ms 10108 KB Output is correct
13 Correct 67 ms 10108 KB Output is correct
14 Correct 80 ms 10108 KB Output is correct
15 Correct 86 ms 10220 KB Output is correct
16 Correct 76 ms 10220 KB Output is correct
17 Correct 89 ms 10244 KB Output is correct
18 Correct 90 ms 10244 KB Output is correct
19 Correct 100 ms 11836 KB Output is correct
20 Correct 5 ms 11836 KB Output is correct
21 Correct 5 ms 11836 KB Output is correct
22 Correct 85 ms 11836 KB Output is correct
23 Correct 67 ms 11836 KB Output is correct
24 Correct 97 ms 11836 KB Output is correct
25 Correct 75 ms 11836 KB Output is correct

Subtask #2
70.0 / 70.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 11836 KB Output is correct
2 Correct 5 ms 11836 KB Output is correct
3 Correct 73 ms 11836 KB Output is correct
4 Correct 80 ms 11836 KB Output is correct
5 Correct 72 ms 11836 KB Output is correct
6 Correct 279 ms 22372 KB Output is correct
7 Correct 4 ms 22372 KB Output is correct
8 Correct 4 ms 22372 KB Output is correct
9 Correct 4 ms 22372 KB Output is correct
10 Correct 4 ms 22372 KB Output is correct
11 Correct 4 ms 22372 KB Output is correct
12 Correct 4 ms 22372 KB Output is correct
13 Correct 5 ms 22372 KB Output is correct
14 Correct 4 ms 22372 KB Output is correct
15 Correct 5 ms 22372 KB Output is correct
16 Correct 5 ms 22372 KB Output is correct
17 Correct 4 ms 22372 KB Output is correct
18 Correct 5 ms 22372 KB Output is correct
19 Correct 4 ms 22372 KB Output is correct
20 Correct 5 ms 22372 KB Output is correct
21 Correct 5 ms 22372 KB Output is correct
22 Correct 5 ms 22372 KB Output is correct
23 Correct 82 ms 22372 KB Output is correct
24 Correct 117 ms 22372 KB Output is correct
25 Correct 69 ms 22372 KB Output is correct
26 Correct 77 ms 22372 KB Output is correct
27 Correct 74 ms 22372 KB Output is correct
28 Correct 75 ms 22372 KB Output is correct
29 Correct 233 ms 22372 KB Output is correct
30 Correct 101 ms 22372 KB Output is correct
31 Correct 104 ms 22372 KB Output is correct
32 Correct 92 ms 22372 KB Output is correct
33 Correct 71 ms 22372 KB Output is correct
34 Correct 73 ms 22372 KB Output is correct
35 Correct 77 ms 22372 KB Output is correct
36 Correct 68 ms 22372 KB Output is correct
37 Correct 288 ms 22548 KB Output is correct
38 Correct 113 ms 22548 KB Output is correct
39 Correct 87 ms 22548 KB Output is correct
40 Correct 100 ms 22548 KB Output is correct
41 Correct 79 ms 22548 KB Output is correct
42 Correct 74 ms 22548 KB Output is correct
43 Correct 81 ms 22548 KB Output is correct
44 Correct 68 ms 22548 KB Output is correct
45 Correct 206 ms 22548 KB Output is correct
46 Correct 106 ms 22548 KB Output is correct
47 Correct 113 ms 22548 KB Output is correct
48 Correct 101 ms 22548 KB Output is correct
49 Correct 66 ms 22548 KB Output is correct
50 Correct 80 ms 22548 KB Output is correct
51 Correct 78 ms 22548 KB Output is correct
52 Correct 79 ms 22548 KB Output is correct
53 Correct 219 ms 22548 KB Output is correct
54 Correct 105 ms 22548 KB Output is correct