Submission #890622

#	Time	Username	Problem	Language	Result	Execution time	Memory
890622		cpptowin	Valley (BOI19_valley)	C++17	100 / 100	149 ms	84820 KiB

valley

#include<bits/stdc++.h>
#define fo(i,d,c) for(int i=d;i<=c;i++)
#define fod(i,c,d) for(int i=c;i>=d;i--)
#define maxn 1000010
#define N 1010
#define fi first
#define se second
#define pb emplace_back
#define en cout<<"\n";
#define int long long
#define inf 1000000000
#define pii pair<int,int>
#define vii vector<pii>
#define lb(x) x&-x
#define bit(i,j) ((i>>j)&1)
#define offbit(i,j) (i^(1<<j))
#define onbit(i,j) (i|(1<<j))
#define vi vector<int>
template <typename T1, typename T2> bool minimize(T1 &a, T2 b){if (a > b) {a = b; return true;} return false;}
template <typename T1, typename T2> bool maximize(T1 &a, T2 b){if (a < b) {a = b; return true;} return false;}
using namespace std;
int par[maxn][20],minn[maxn][20];
int magic[maxn];
vii ke[maxn];
int n;
int d[maxn];
pii edge[maxn];
int S,E,Q;
bool shop[maxn];
int h[maxn];
void calcmagic(int u,int parent)
{
    if(shop[u]) magic[u] = d[u];
    for(auto [v,w] : ke[u])
    {
        if(v == parent) continue;
        par[v][0] = u;
        h[v] = h[u] + 1;
        d[v] = d[u] + w;
        calcmagic(v,u);
        magic[u] = min(magic[u],magic[v]);
    }
}
int lca(int u, int v)
{
    if (h[u] < h[v])
        swap(u, v);
    int del = h[u] - h[v];
    fod(i, 19, 0) if (bit(del, i)) u = par[u][i];
    if (u == v)
        return u;
    fod(i, 19, 0) if (par[u][i] != par[v][i]) u = par[u][i], v = par[v][i];
    return par[u][0];
}
main()
{
    #define name "TASK"
    if(fopen(name".inp","r"))
    {
       freopen(name".inp","r",stdin);
       freopen(name".out","w",stdout);
    }
    ios_base::sync_with_stdio(false);cin.tie(NULL);
    cin >> n >> S >> Q >> E;
    fo(i,1,n - 1)
    {
        int u,v,w;
        cin >> u >> v >> w;
        ke[u].pb(v,w);
        ke[v].pb(u,w);
        edge[i] = {u,v};
    }
    fo(i,1,S)
    {
        int x;
        cin >> x;
        shop[x] = 1;
    }
    fo(i,1,n) magic[i] = 1e18;
    calcmagic(E,E);
//    fo(i,1,n) cout << magic[i] << ' ';en;
    fo(i,1,n) if(magic[i] < 1e18) magic[i] = magic[i] - 2 * d[i];
//    fo(i,1,n) cout << magic[i] << ' ';en;
    fo(j,1,19) fo(i,1,n) par[i][j] = par[par[i][j - 1]][j - 1];
    fo(i,1,n) minn[i][0] = magic[par[i][0]];
    fo(j,1,19) fo(i,1,n) minn[i][j] = min(minn[i][j - 1],minn[par[i][j - 1]][j - 1]);
//    cout << lca()
    while(Q--)
    {
        int id,r;
        cin >> id >> r;
        if(lca(edge[id].se,r) != edge[id].se or lca(edge[id].fi,r) != edge[id].fi) cout << "escaped \n";
        else
        {
            int val = d[r];
            int ans = 1e18;
            int del = h[r] - max(h[edge[id].fi],h[edge[id].se]);
            ans = min(ans,magic[r]);
            fod(i,19,0) if(bit(del,i)) ans = min(ans,minn[r][i]),r = par[r][i];
            if(ans == 1e18) cout << "oo";
            else cout << val + ans;
            en;
        }
    }
}

Compilation message (stderr)

valley.cpp:55:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   55 | main()
      | ^~~~
valley.cpp: In function 'int main()':
valley.cpp:60:15: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   60 |        freopen(name".inp","r",stdin);
      |        ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
valley.cpp:61:15: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   61 |        freopen(name".out","w",stdout);
      |        ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 9 / 9
• Subtask 2: 27 / 27
• Subtask 3: 23 / 23
• Subtask 4: 41 / 41