Submission #462464

#	Time	Username	Problem	Language	Result	Execution time	Memory
462464		Yeboi	Pipes (BOI13_pipes)	C++14	100 / 100	545 ms	36504 KiB

pipes

#include <bits/stdc++.h>
#define ll long long
#define mod 998244353
#define fastio() ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL)
#define rep(i,s) for(ll i=0; i<s ; i++)
#define f(i,a,b) for(ll i(a); i<b ; i++)
const ll INF = 1000000000000000000;
const ll N = 100001;
const ll MOD = 1000000007;
const ll modi = 1000000007;
const ll MAXN = 10000000000;    
const ll rootval = 319;
using namespace std;

ll upedge[N];
ll ngood[N];
vector<ll> adj[N];
ll arr[N];
ll par[N];
ll n;
void dfs1(ll v, ll p){
    ll sum = 0;
    for(auto u : adj[v]){
        if(u == p){
            continue;
        }
        else{
            if(upedge[u] == -1){
                dfs1(u,v);
            }
            sum += upedge[u];
        }
    }
    upedge[v] = arr[v] - sum;
}
void dfs2(ll v, ll p){
    ll sum = 0;
    for(auto u : adj[v]){
        if(u == p || ngood[u] == -1){
            continue;
        }
        else{
            if(upedge[u] == -1){
                dfs2(u,v);
            }
            sum += upedge[u];
        }
    }
    upedge[v] = arr[v] - sum;
}
void parents(ll v, ll p){
    for(auto u : adj[v]){
        if(u == p){
            continue;
        }
        else{
            par[u] = v;
            parents(u,v);
        }
    }
}
void parents2(ll v, ll p){
    for(auto u : adj[v]){
        if(u == p || ngood[u] == -1){
            continue;
        }
        else{
            par[u] = v;
            parents2(u,v);
        }
    }
}
vector<bool> visited;
vector<ll> parent;
ll cycle_start, cycle_end;

bool dfs(ll v, ll par) { // passing vertex and its parent vertex
    visited[v] = true;
    for (ll u : adj[v]) {
        if(u == par) continue; // skipping edge to parent vertex
        if (visited[u]) {
            cycle_end = v;
            cycle_start = u;
            return true;
        }
        parent[u] = v;
        if (dfs(u, parent[u]))
            return true;
    }
    return false;
}

vector<ll> find_cycle() {
    visited.assign(n, false);
    parent.assign(n, -1);
    cycle_start = -1;
    vector<ll> cycle;
    for (ll v = 0; v < n; v++) {
        if (!visited[v] && dfs(v, parent[v]))
            break;
    }

    if (cycle_start == -1) {
        return cycle;
    } else {
        vector<ll> cycle;
        cycle.push_back(cycle_start);
        for (ll v = cycle_end; v != cycle_start; v = parent[v]){
            cycle.push_back(v);
        }
        reverse(cycle.begin(), cycle.end());
        return cycle;
    }
}
int main(){
    fastio();
    ll m;
    cin >> n >> m;
    vector<pair<ll,ll>> edges;
    rep(i,n){
        cin >> arr[i];
        upedge[i] = -1;
    }
    rep(i,m){
        ll u,v;
        cin >> u >> v;
        --u,--v;
        adj[u].push_back(v);
        adj[v].push_back(u);
        edges.push_back(make_pair(u,v));
    }
    if(m == n-1){
        ll root = 0;
        rep(i,n){
            if(adj[i].size() != 1){
                root = i;
                break;
            }
        }
        rep(i,n){
            if(adj[i].size() == 1){
                upedge[i] = arr[i];
            }
        }
        dfs1(root,-1);
        parents(root,-1);
        par[root] = -1;
        map<pair<ll,ll>,ll> mp;
        rep(i,n){
            if(par[i] == -1){
                continue;
            }
            else{
                mp[{i,par[i]}] = upedge[i];
                mp[{par[i],i}] = upedge[i];
            }
        }
        rep(i,edges.size()){
            ll u = edges[i].first;
            ll v = edges[i].second;
            cout << 2*mp[{u,v}] << endl;
        }
    }
    else if(m == n){
        // one cycle exists so just find that one cycle done?
        rep(i,n){
            if(adj[i].size() == 1){
                upedge[i] = arr[i];
            }
        }
        vector<ll> cycle = find_cycle();
        rep(i,cycle.size()){
            ngood[cycle[i]] = -1;
        }
        if(cycle.size() % 2 == 0){
            cout << 0 << endl;
        }
        else{
            rep(j,cycle.size()){
                ll i = cycle[j];
                dfs2(i,-1);
                parents2(i,-1);
                par[i] = -1;
            }
            map<pair<ll,ll>,ll> mp;
            map<pair<ll,ll>,ll> mp2;
            rep(i,n){
                if(par[i] != -1){
                    mp[{par[i],i}] = upedge[i];
                    mp[{i,par[i]}] = upedge[i];
                    mp2[{par[i],i}] = 2*upedge[i];
                    mp2[{i,par[i]}] = 2*upedge[i];
                }
            }
            rep(i,cycle.size()){
                for(auto u : adj[cycle[i]]){
                    if(ngood[u] == -1){
                        continue;
                    }
                    else{
                        arr[cycle[i]] = arr[cycle[i]] - mp[{cycle[i],u}];
                    }
                }
            }
            ll val = arr[cycle[0]];
            f(i,1,cycle.size()){
                if(i%2 == 1){
                    val += arr[cycle[i]];
                }
                else{
                    val = val - arr[cycle[i]];
                }
            }
            mp2[{cycle[0],cycle[1]}] = val;
            mp2[{cycle[1],cycle[0]}] = val;
            f(i,1,cycle.size()-1){
                mp2[{cycle[i],cycle[i+1]}] = 2*arr[cycle[i]] - mp2[{cycle[i-1],cycle[i]}];
                mp2[{cycle[i+1],cycle[i]}] = mp2[{cycle[i],cycle[i+1]}];
            }
            mp2[{cycle[cycle.size()-1],cycle[0]}] = 2*arr[cycle[cycle.size()-1]] - mp2[{cycle[cycle.size()-1],cycle[cycle.size()-2]}];
            mp2[{cycle[0],cycle[cycle.size()-1]}] = mp2[{cycle[cycle.size()-1],cycle[0]}];
            rep(i,edges.size()){
                cout << mp2[{edges[i].first,edges[i].second}] << endl;
            }
        }
    }
    else if(m > n){
        cout << 0 << endl;
    }
}

Compilation message (stderr)

pipes.cpp: In function 'int main()':
pipes.cpp:5:31: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    5 | #define rep(i,s) for(ll i=0; i<s ; i++)
......
  158 |         rep(i,edges.size()){
      |             ~~~~~~~~~~~~~~     
pipes.cpp:158:9: note: in expansion of macro 'rep'
  158 |         rep(i,edges.size()){
      |         ^~~
pipes.cpp:5:31: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    5 | #define rep(i,s) for(ll i=0; i<s ; i++)
......
  172 |         rep(i,cycle.size()){
      |             ~~~~~~~~~~~~~~     
pipes.cpp:172:9: note: in expansion of macro 'rep'
  172 |         rep(i,cycle.size()){
      |         ^~~
pipes.cpp:5:31: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    5 | #define rep(i,s) for(ll i=0; i<s ; i++)
......
  179 |             rep(j,cycle.size()){
      |                 ~~~~~~~~~~~~~~ 
pipes.cpp:179:13: note: in expansion of macro 'rep'
  179 |             rep(j,cycle.size()){
      |             ^~~
pipes.cpp:5:31: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    5 | #define rep(i,s) for(ll i=0; i<s ; i++)
......
  195 |             rep(i,cycle.size()){
      |                 ~~~~~~~~~~~~~~ 
pipes.cpp:195:13: note: in expansion of macro 'rep'
  195 |             rep(i,cycle.size()){
      |             ^~~
pipes.cpp:6:32: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    6 | #define f(i,a,b) for(ll i(a); i<b ; i++)
......
  206 |             f(i,1,cycle.size()){
      |               ~~~~~~~~~~~~~~~~  
pipes.cpp:206:13: note: in expansion of macro 'f'
  206 |             f(i,1,cycle.size()){
      |             ^
pipes.cpp:6:32: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<long long int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    6 | #define f(i,a,b) for(ll i(a); i<b ; i++)
......
  216 |             f(i,1,cycle.size()-1){
      |               ~~~~~~~~~~~~~~~~~~
pipes.cpp:216:13: note: in expansion of macro 'f'
  216 |             f(i,1,cycle.size()-1){
      |             ^
pipes.cpp:5:31: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::vector<std::pair<long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    5 | #define rep(i,s) for(ll i=0; i<s ; i++)
......
  222 |             rep(i,edges.size()){
      |                 ~~~~~~~~~~~~~~ 
pipes.cpp:222:13: note: in expansion of macro 'rep'
  222 |             rep(i,edges.size()){
      |             ^~~

• Subtask 1: 30 / 30
• Subtask 2: 70 / 70