oj.uz

Submission #741804

# Submission time Handle Problem Language Result Execution time Memory
741804 2023-05-15T00:19:17 Z rainliofficial Stations (IOI20_stations) C++17
100 / 100
 971 ms 884 KB 
#include "stations.h"
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
template<class T> bool ckmin(T& a, const T& b) { return b < a ? a = b, 1 : 0; }
template<class T> bool ckmax(T& a, const T& b) { return a < b ? a = b, 1 : 0; }
#define sz(x) (int)x.size()
#define all(x) begin(x), end(x)

/* 
Date: 2023/05/14 14:06
Problem Link: 
Topic(s):
Reflection:
Solution Notes:
We want to determine for two nodes (A, B), if A is an ancestor of B. 
Normally, an Euler tour can accomplish this. 
To encode the in and out times into one single number, we would need somewhere around 1000^2 + 1000 ~= 10^6 numbers.

The next logical step is how to not encode the in and out times. 
Consider not storing BOTH the in and out for each node. Since we are given the neighbors, let p be the parent and c be some children, 
we can still determine if a node A within the subtree of p by checking the range [in[p], max(out[c])] . 
Consider storing everything an even depth away from the root to be in, and odd to be out. 
We know whether a node has in vs. out time by checking if it is even or odd. 
Now, we can compress down to 2*N states. 

We can reduce to N states by compressing the values, because only their relative sizes matter. 
We can determine if a node has the in time or out time by determining if:
max(label of neighbor) > label[current] -> current has in time
max(label of neighbor) < label[current] -> current has out time
label[current] == 0 -> the root
*/

const int MAXN = 1000+5, INF = 1e9;
int n, in[MAXN], out[MAXN], dep[MAXN], timer = 0;
vector<int> arr[MAXN];

void dfs(int at, int p, int d){
    dep[at] = d;
    in[at] = timer++;
    for (int u : arr[at]){
        if (u != p){
            dfs(u, at, d+1);
        }
    }
    out[at] = timer++;
}
std::vector<int> label(int n, int k, std::vector<int> u, std::vector<int> v) {
    for (int i = 0; i<n; i++) arr[i].clear();
	vector<int> labels(n);
    for (int i=0; i<n-1; i++){
        arr[u[i]].push_back(v[i]);
        arr[v[i]].push_back(u[i]);
    }
    dfs(0, -1, 0);
    vector<int> all_labels;
    for (int i=0; i<n; i++){
        if (dep[i] % 2 == 0){
            all_labels.push_back(in[i]);
            labels[i] = in[i];
        }else{
            all_labels.push_back(out[i]);
            labels[i] = out[i];
        }
    }
    sort(all(all_labels));
    for (int i=0; i<n; i++){
        labels[i] = lower_bound(all(all_labels), labels[i]) - all_labels.begin();
    }
	return labels;
}

int find_next_station(int s, int t, std::vector<int> c) {
    if (sz(c) == 1) return c[0];
    if (s < c[0]){
        // s = in
        for (int i=0; i<(s == 0 ? sz(c) : sz(c) - 1); i++){
            if ((i == 0 ? s + 1 : c[i-1] + 1) <= t && c[i] >= t){
                return c[i];
            }
        }
        return c[sz(c)-1]; // go to parent
    }else{
        // s = out
        for (int i=1; i<sz(c); i++){
            if (t >= c[i] && t <= (i != sz(c) - 1 ? c[i+1]-1 : s - 1)){
                return c[i];
            }
        }
        return c[0];
    }
}


// int main(){
//     cin.tie(0); ios_base::sync_with_stdio(0);
//     freopen("file.in", "r", stdin);
//     // freopen("file.out", "w", stdout);
    
// }

Subtask #1
5.0 / 5.0

# Verdict Execution time Memory Grader output
1 Correct 541 ms 684 KB Output is correct
2 Correct 445 ms 536 KB Output is correct
3 Correct 899 ms 528 KB Output is correct
4 Correct 624 ms 528 KB Output is correct
5 Correct 598 ms 528 KB Output is correct
6 Correct 495 ms 520 KB Output is correct
7 Correct 527 ms 532 KB Output is correct
8 Correct 3 ms 628 KB Output is correct
9 Correct 3 ms 492 KB Output is correct
10 Correct 0 ms 500 KB Output is correct

Subtask #2
8.0 / 8.0

# Verdict Execution time Memory Grader output
1 Correct 425 ms 532 KB Output is correct
2 Correct 576 ms 572 KB Output is correct
3 Correct 951 ms 420 KB Output is correct
4 Correct 698 ms 528 KB Output is correct
5 Correct 571 ms 524 KB Output is correct
6 Correct 418 ms 548 KB Output is correct

Subtask #3
16.0 / 16.0

# Verdict Execution time Memory Grader output
1 Correct 527 ms 544 KB Output is correct
2 Correct 531 ms 652 KB Output is correct
3 Correct 971 ms 528 KB Output is correct
4 Correct 858 ms 524 KB Output is correct
5 Correct 492 ms 544 KB Output is correct
6 Correct 483 ms 628 KB Output is correct
7 Correct 493 ms 508 KB Output is correct
8 Correct 4 ms 624 KB Output is correct
9 Correct 5 ms 492 KB Output is correct
10 Correct 1 ms 416 KB Output is correct
11 Correct 728 ms 520 KB Output is correct
12 Correct 472 ms 652 KB Output is correct
13 Correct 492 ms 780 KB Output is correct
14 Correct 506 ms 548 KB Output is correct
15 Correct 55 ms 592 KB Output is correct
16 Correct 63 ms 548 KB Output is correct
17 Correct 97 ms 704 KB Output is correct

Subtask #4
10.0 / 10.0

# Verdict Execution time Memory Grader output
1 Correct 822 ms 548 KB Output is correct
2 Correct 707 ms 536 KB Output is correct
3 Correct 591 ms 532 KB Output is correct
4 Correct 1 ms 620 KB Output is correct
5 Correct 4 ms 496 KB Output is correct
6 Correct 2 ms 620 KB Output is correct
7 Correct 490 ms 536 KB Output is correct
8 Correct 907 ms 516 KB Output is correct
9 Correct 595 ms 532 KB Output is correct
10 Correct 539 ms 528 KB Output is correct
11 Correct 5 ms 628 KB Output is correct
12 Correct 6 ms 628 KB Output is correct
13 Correct 2 ms 620 KB Output is correct
14 Correct 4 ms 620 KB Output is correct
15 Correct 1 ms 632 KB Output is correct
16 Correct 471 ms 432 KB Output is correct
17 Correct 522 ms 420 KB Output is correct
18 Correct 615 ms 420 KB Output is correct
19 Correct 512 ms 544 KB Output is correct
20 Correct 497 ms 548 KB Output is correct

Subtask #5
61.0 / 61.0

# Verdict Execution time Memory Grader output
1 Correct 553 ms 544 KB Output is correct
2 Correct 491 ms 660 KB Output is correct
3 Correct 830 ms 532 KB Output is correct
4 Correct 524 ms 548 KB Output is correct
5 Correct 593 ms 528 KB Output is correct
6 Correct 412 ms 544 KB Output is correct
7 Correct 408 ms 528 KB Output is correct
8 Correct 2 ms 492 KB Output is correct
9 Correct 4 ms 620 KB Output is correct
10 Correct 1 ms 492 KB Output is correct
11 Correct 505 ms 528 KB Output is correct
12 Correct 561 ms 544 KB Output is correct
13 Correct 897 ms 544 KB Output is correct
14 Correct 701 ms 544 KB Output is correct
15 Correct 540 ms 548 KB Output is correct
16 Correct 403 ms 536 KB Output is correct
17 Correct 522 ms 544 KB Output is correct
18 Correct 462 ms 784 KB Output is correct
19 Correct 399 ms 648 KB Output is correct
20 Correct 433 ms 544 KB Output is correct
21 Correct 48 ms 572 KB Output is correct
22 Correct 69 ms 704 KB Output is correct
23 Correct 111 ms 656 KB Output is correct
24 Correct 4 ms 628 KB Output is correct
25 Correct 5 ms 620 KB Output is correct
26 Correct 3 ms 632 KB Output is correct
27 Correct 4 ms 496 KB Output is correct
28 Correct 1 ms 620 KB Output is correct
29 Correct 542 ms 528 KB Output is correct
30 Correct 526 ms 544 KB Output is correct
31 Correct 517 ms 544 KB Output is correct
32 Correct 580 ms 528 KB Output is correct
33 Correct 488 ms 420 KB Output is correct
34 Correct 325 ms 636 KB Output is correct
35 Correct 372 ms 672 KB Output is correct
36 Correct 474 ms 756 KB Output is correct
37 Correct 460 ms 636 KB Output is correct
38 Correct 480 ms 656 KB Output is correct
39 Correct 438 ms 884 KB Output is correct
40 Correct 469 ms 668 KB Output is correct
41 Correct 390 ms 660 KB Output is correct
42 Correct 52 ms 620 KB Output is correct
43 Correct 114 ms 676 KB Output is correct
44 Correct 133 ms 548 KB Output is correct
45 Correct 168 ms 548 KB Output is correct
46 Correct 298 ms 528 KB Output is correct
47 Correct 346 ms 528 KB Output is correct
48 Correct 52 ms 772 KB Output is correct
49 Correct 62 ms 676 KB Output is correct