Submission #1111443

#	Time	Username	Problem	Language	Result	Execution time	Memory
1111443		giaminh2211	Valley (BOI19_valley)	C++14	100 / 100	199 ms	37704 KiB

valley

#include<bits/stdc++.h>
#define fi first
#define se second

using namespace std;
using ll=long long;

const int N=1e5+13;

struct Segtree{
    ll st[N << 2];
    ll lazy[N << 2];

    void fix(int id, int l, int r){
        if(!lazy[id]) return;
        st[id] += lazy[id];
        if(l!=r){
            lazy[id << 1] += lazy[id];
            lazy[id << 1 | 1] += lazy[id];
        }
        lazy[id]=0;
    }

    void update(int id, int l, int r, int u, int v, ll val){
        fix(id, l, r);
        if(l > v || r < u) return;
        if(u<=l && r<=v){
            lazy[id]+=val;
            fix(id, l, r);
            return;
        }
        int mid=l+r >> 1;
        update(id << 1, l, mid, u, v, val);
        update(id << 1 | 1, mid+1, r, u, v, val);
        st[id]=min(st[id << 1], st[id << 1 | 1]);
    }

    ll get(int id, int l, int r, int u, int v){
        fix(id, l, r);
        if(l > v || r < u) return 1e18;
        if(u<=l && r<=v){
            return st[id];
        }
        int mid=l+r >> 1;
        ll get1=get(id << 1, l, mid, u, v);
        ll get2=get(id << 1 | 1, mid+1, r, u, v);
        return min(get1, get2);
    }
} st;

int n, s, q, h;
vector<pair<int, ll>> g[N];
int x[N], y[N], tmp, _x, _y;
ll w;
ll d[N];
bool mark[N];
ll val[N];
int par[N];
int tin[N];
int tout[N];
int tdfs;
ll res[N];
vector<pair<int, int>> qr[N];

void scan(){
    cin >> n >> s >> q >> h;
    for(int i=1; i<n; i++){
        cin >> x[i] >> y[i] >> w;
        g[x[i]].emplace_back(y[i], w);
        g[y[i]].emplace_back(x[i], w);
    }
    while(s--){
        cin >> tmp;
        mark[tmp]=1;
    }
    for(int i=1; i<=q; i++){
        cin >> _x >> _y;
        qr[_y].push_back({_x, i});
    }
}

void pre_dfs(int v){
    ++tdfs;
    tin[v]=tdfs;
    for(auto c: g[v]){
        if(c.fi==par[v]) continue;
        par[c.fi]=v;
        d[c.fi]=d[v]+c.se;
        pre_dfs(c.fi);
    }
    tout[v]=tdfs;
}

bool insub(int u, int v){
    return tin[u] <= tin[v] && tin[v] <= tout[u];
}

void dfs(int v){
    for(auto r: qr[v]){
        if(par[x[r.fi]]==y[r.fi]) swap(x[r.fi], y[r.fi]); // now x[r] is par
        int cc=0;
        int ver=y[r.fi];
        cc += insub(ver, h);
        cc += insub(ver, v);
        if(cc!=1){
            res[r.se]=-1;
        }
        else{
            if(insub(ver, v)){
            	res[r.se]=st.get(1, 1, n, tin[ver], tout[ver]);
            }
            else{
                ll val1=st.get(1, 1, n, 1, tin[ver]-1);
                ll val2=st.get(1, 1, n, tout[ver]+1, n);
                res[r.se]=min(val1, val2);
            }
        }
    }
    for(auto c: g[v]){
        if(c.fi==par[v]) continue;
        st.update(1, 1, n, 1, n, c.se);
        st.update(1, 1, n, tin[c.fi], tout[c.fi], -2*c.se);
        dfs(c.fi);
        st.update(1, 1, n, 1, n, -c.se);
        st.update(1, 1, n, tin[c.fi], tout[c.fi], 2*c.se);
    }
}

void solve(){
    pre_dfs(1);
    for(int i=1; i<=n; i++){
        if(mark[i]) val[i]=d[i];
        else val[i]=1e18;
        st.update(1, 1, n, tin[i], tin[i], val[i]);
    }
    dfs(1);
    for(int i=1; i<=q; i++){
        if(res[i]==-1) cout << "escaped";
        else if(res[i] >= 1e17) cout << "oo";
        else cout << res[i];
        cout << '\n';
    }
}

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    scan();
    solve();
}

Compilation message (stderr)

valley.cpp: In member function 'void Segtree::update(int, int, int, int, int, ll)':
valley.cpp:32:18: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   32 |         int mid=l+r >> 1;
      |                 ~^~
valley.cpp: In member function 'll Segtree::get(int, int, int, int, int)':
valley.cpp:44:18: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
   44 |         int mid=l+r >> 1;
      |                 ~^~

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