oj.uz

Submission #1004584

# Submission time Handle Problem Language Result Execution time Memory
1004584 2024-06-21T10:04:10 Z anango Valley (BOI19_valley) C++17
100 / 100
 369 ms 67276 KB 
#include <bits/stdc++.h>
#define int long long
using namespace std;
int n,s,q,e;
int INF = 1LL<<60;
vector<vector<pair<int,int>>> adjlist;
vector<int> dist;
vector<int> dp1;
vector<int> is_shop;
vector<int> parent;
vector<int> depth;
vector<int> blubber;
vector<int> preorder, postorder;
int current = 0;

int MSB(int x) {
    int t=1;
    int ct=0;
    while (t<=x) {
        t*=2;
        ct++;

    }
    return ct-1;
}

void dfs(int node, int par) {
    //cout << node <<" " << par << endl;
    preorder[node] = current;
    current++;
    for (auto j:adjlist[node]) {
        int w = j.second;
        int x = j.first;
        if (x!=par) {
            dist[x] = min(dist[x], dist[node]+w);
            depth[x] = depth[node]+1;
            parent[x] = node;
            dfs(x,node);
            dp1[node] = min(dp1[node],dp1[x]+w);
        }
    }
    postorder[node] = current;
    current++;
}


signed main() {
    #ifndef ONLINE_JUDGE
        // for getting input from input.txt
        //freopen("input.txt", "r", stdin);
        // for writing output to output.txt
        //freopen("output.txt", "w", stdout);
    #endif
    /*#ifdef ONLINE_JUDGE
    	ios_base::sync_with_stdio(false);
    	cin.tie(NULL);
    #endif*/ //fast IO 
    cin >> n >> s >> q >> e;
    e--;
    adjlist=vector<vector<pair<int,int>>>(n);
    dist=dp1=blubber=vector<int>(n,INF);
    is_shop = depth = vector<int>(n,0);
    preorder = postorder = parent = vector<int>(n,-1);
    vector<pair<int,int>> edges;
    for (int i=0; i<n-1; i++) {
        int a,b,w;
        cin >> a >> b >> w;
        a--;
        b--;
        //cout << a <<" " << b <<" " << w << " " << adjlist.size() << endl;
        adjlist[a].push_back({b,w});
        adjlist[b].push_back({a,w});
        edges.push_back({a,b});
    }
    for (int i=0; i<s; i++) {
        int x;
        cin >> x;
        x--;
        is_shop[x] = 1;
        dp1[x] = 0;
    }
    dist[e] = 0;
    dfs(e,-1);
    for (int i=0; i<n; i++) {
        if (dp1[i]==INF) {
            blubber[i] = INF;
        }
        else {
            blubber[i] = dp1[i]-dist[i];
        }
    }
    int K = 22;

    vector<vector<int>> multiparent(n,vector<int>(K,-1));
    vector<vector<int>> minima(n,vector<int>(K,INF)); //min value of blubber upto 2^j ancestors
    for (int i=0; i<n; i++) {
        multiparent[i][0] = parent[i];
        minima[i][0] = blubber[i];
    }
    parent[e] = multiparent[e][0] = e;
    //cout << endl;
    for (int p=1; p<K; p++) {
        for (int i=0; i<n; i++) {
            //cout << i <<" " << p << " " << multiparent[i][p-1] << endl;
            multiparent[i][p] = multiparent[multiparent[i][p-1]][p-1];
            minima[i][p] = min(minima[i][p-1], minima[multiparent[i][p-1]][p-1]);
        }
    }
    for (int qu=0; qu<q; qu++) {
        int I,R;
        cin >> I >> R;
        I--;
        R--;
        int a = edges[I].first;
        int b = edges[I].second;
        if (depth[a]>depth[b]) {
            swap(a,b);
        }
        //care about b (higher depth)
        //if R is not in the subtree of b then it's escaped
        //cout << b <<" " << R<<" " << preorder[b] <<" " << preorder[R] << " " << postorder[R] << " " << postorder[b] << endl;
        if (!(preorder[b]<=preorder[R] && preorder[R]<=postorder[R] && postorder[R]<=postorder[b])) {
            cout << "escaped" << endl;
        }
        else {
            //binary jump
            int ans = INF;
            int cur = R;
            int tdepth = depth[b];
            int cdepth = depth[R];
            int fdist = dist[R];
            /*for (int p=K-1; p>=0; p--) {
                if (cdepth-(1<<p) >= tdepth) {
                    ans=min(ans,fdist+minima[cur][p]);
                    //cout << "DOING " << p <<" " << cur << " " << fdist+minima[cur][p] << endl;
                    cdepth-=1<<p;
                    cur=multiparent[cur][p];
                }
            }*/
            while (cdepth>tdepth) {
                int lp = MSB(cdepth-tdepth);
                ans=min(ans,fdist+minima[cur][lp]);
                cdepth-=1<<lp;
                cur=multiparent[cur][lp];
            }
            ans=min(ans,fdist+minima[cur][0]);
            if (ans>1LL<<58) {
                cout << "oo" << endl;
            }
            else {
                cout << ans << endl;
            }
        }



    }

    for (int i=0; i<n; i++) {
        //cout << i <<" " << preorder[i] <<" " << postorder[i] << endl;
    }
    /*for (int p=0; p<K; p++) {
        cout << "lifting " << p << endl;
        for (int i=0; i<n; i++) {
            cout << i <<" " << multiparent[i][p] <<" " << minima[i][p] << endl;
        }
    }



    cout << "blubbers" << endl;
    for (int i=0; i<n; i++) {
        cout << i << " " << dist[i] << " " << dp1[i] << " " << blubber[i] << endl;
    }*/


    
}

Subtask #1
9.0 / 9.0

# Verdict Execution time Memory Grader output
1 Correct 16 ms 604 KB Output is correct
2 Correct 11 ms 604 KB Output is correct
3 Correct 12 ms 556 KB Output is correct
4 Correct 11 ms 604 KB Output is correct

Subtask #2
27.0 / 27.0

# Verdict Execution time Memory Grader output
1 Correct 16 ms 604 KB Output is correct
2 Correct 11 ms 604 KB Output is correct
3 Correct 12 ms 556 KB Output is correct
4 Correct 11 ms 604 KB Output is correct
5 Correct 3 ms 860 KB Output is correct
6 Correct 2 ms 856 KB Output is correct
7 Correct 2 ms 860 KB Output is correct
8 Correct 3 ms 1116 KB Output is correct
9 Correct 2 ms 860 KB Output is correct
10 Correct 2 ms 860 KB Output is correct
11 Correct 2 ms 964 KB Output is correct
12 Correct 2 ms 860 KB Output is correct
13 Correct 3 ms 860 KB Output is correct
14 Correct 2 ms 1056 KB Output is correct

Subtask #3
23.0 / 23.0

# Verdict Execution time Memory Grader output
1 Correct 258 ms 60724 KB Output is correct
2 Correct 264 ms 62344 KB Output is correct
3 Correct 282 ms 62716 KB Output is correct
4 Correct 320 ms 64448 KB Output is correct
5 Correct 270 ms 64524 KB Output is correct
6 Correct 284 ms 66496 KB Output is correct

Subtask #4
41.0 / 41.0

# Verdict Execution time Memory Grader output
1 Correct 16 ms 604 KB Output is correct
2 Correct 11 ms 604 KB Output is correct
3 Correct 12 ms 556 KB Output is correct
4 Correct 11 ms 604 KB Output is correct
5 Correct 3 ms 860 KB Output is correct
6 Correct 2 ms 856 KB Output is correct
7 Correct 2 ms 860 KB Output is correct
8 Correct 3 ms 1116 KB Output is correct
9 Correct 2 ms 860 KB Output is correct
10 Correct 2 ms 860 KB Output is correct
11 Correct 2 ms 964 KB Output is correct
12 Correct 2 ms 860 KB Output is correct
13 Correct 3 ms 860 KB Output is correct
14 Correct 2 ms 1056 KB Output is correct
15 Correct 258 ms 60724 KB Output is correct
16 Correct 264 ms 62344 KB Output is correct
17 Correct 282 ms 62716 KB Output is correct
18 Correct 320 ms 64448 KB Output is correct
19 Correct 270 ms 64524 KB Output is correct
20 Correct 284 ms 66496 KB Output is correct
21 Correct 295 ms 61892 KB Output is correct
22 Correct 243 ms 61636 KB Output is correct
23 Correct 281 ms 61892 KB Output is correct
24 Correct 276 ms 64192 KB Output is correct
25 Correct 306 ms 67052 KB Output is correct
26 Correct 236 ms 61888 KB Output is correct
27 Correct 269 ms 61828 KB Output is correct
28 Correct 269 ms 61824 KB Output is correct
29 Correct 267 ms 63864 KB Output is correct
30 Correct 290 ms 64960 KB Output is correct
31 Correct 275 ms 61892 KB Output is correct
32 Correct 272 ms 61772 KB Output is correct
33 Correct 259 ms 62100 KB Output is correct
34 Correct 369 ms 63920 KB Output is correct
35 Correct 297 ms 67276 KB Output is correct
36 Correct 298 ms 63764 KB Output is correct