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Submission #109299

# Submission time Handle Problem Language Result Execution time Memory
109299 2019-05-06T06:13:33 Z PeppaPig Beads and wires (APIO14_beads) C++14
100 / 100
 294 ms 30952 KB 
#include <bits/stdc++.h>

#define pii pair<int, int>
#define x first
#define y second

using namespace std;

const int N = 2e5+5;

/*
0 - Parent edge any color, No node with 2 blue edges directed to its children
1 - Parent edge must be blue, No node with 2 blue edges directed to its children
2 - Parent edge any color, 1 node in subtree with 2 blue edges directed to its children
3 - Parent edge must be blue, 1 node in subtree with 2 blue edges directed to its children
*/

int n, dp[N][4];
vector<pii> g[N];

void dfs(int u, int p) {
    for(pii v : g[u]) if(v.x != p) dfs(v.x, u);
    vector<int> V, W, M;
    vector<pii> D1, D2;
    for(pii v : g[u]) if(v.x != p) {
        V.emplace_back(v.x), W.emplace_back(v.y);
        M.emplace_back(max(dp[v.x][0], dp[v.x][1] + v.y));
        D1.emplace_back(dp[v.x][0] + v.y - M.back(), v.x);
        D2.emplace_back(dp[v.x][2] + v.y - M.back(), v.x);
    }
    sort(D1.begin(), D1.end(), greater<pii>());
    sort(D2.begin(), D2.end(), greater<pii>());

    dp[u][1] = dp[u][2] = dp[u][3] = -1e9;

    //Base Case
    for(int i = 0; i < M.size(); i++) dp[u][0] += M[i];
    //Directed one blue edge to 0-child, the other to 1-child
    for(int i = 0; i < min(2, (int)D1.size()); i++) 
        for(int j = 0; j < min(2, (int)D2.size()); j++)
            if(D1[i].y != D2[j].y) dp[u][2] = max(dp[u][2], dp[u][0] + D1[i].x + D2[j].x);
    
    //Directed 2 blue edges to 2 0-child
    if(D1.size() > 1) dp[u][2] = max(dp[u][2], dp[u][0] + D1[0].x + D1[1].x);

    //Directed 1 blue edges to 0-child, to be paired in the future
    //Directed 1 blue edges to 2-child, to be paired in the future
    for(int i = 0; i < M.size(); i++) {
        dp[u][1] = max(dp[u][1], dp[u][0] - M[i] + dp[V[i]][0] + W[i]);
        dp[u][3] = max(dp[u][3], dp[u][0] - M[i] + dp[V[i]][2] + W[i]);
    }

    //Merge with 2-child, or pair edge with 3-child
    for(int i = 0; i < M.size(); i++) 
        dp[u][2] = max(dp[u][2], dp[u][0] - M[i] + max(dp[V[i]][2], dp[V[i]][3] + W[i])); 
}

int main() {
    scanf("%d", &n);
    for(int i = 1, a, b, c; i < n; i++) {
        scanf("%d %d %d", &a, &b, &c);
        g[a].emplace_back(b, c), g[b].emplace_back(a, c);
    }
    dfs(1, 1);
    printf("%d\n", max(dp[1][0], dp[1][2]));

    return 0;
}

Compilation message

beads.cpp: In function 'void dfs(int, int)':
beads.cpp:37:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 0; i < M.size(); i++) dp[u][0] += M[i];
                    ~~^~~~~~~~~~
beads.cpp:48:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 0; i < M.size(); i++) {
                    ~~^~~~~~~~~~
beads.cpp:54:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 0; i < M.size(); i++) 
                    ~~^~~~~~~~~~
beads.cpp: In function 'int main()':
beads.cpp:59:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &n);
     ~~~~~^~~~~~~~~~
beads.cpp:61:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d %d %d", &a, &b, &c);
         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
13.0 / 13.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 4992 KB Output is correct
2 Correct 5 ms 4992 KB Output is correct
3 Correct 5 ms 4992 KB Output is correct
4 Correct 6 ms 4992 KB Output is correct
5 Correct 5 ms 4992 KB Output is correct
6 Correct 5 ms 4992 KB Output is correct
7 Correct 5 ms 4992 KB Output is correct
8 Correct 6 ms 4992 KB Output is correct
9 Correct 5 ms 4992 KB Output is correct
10 Correct 6 ms 4992 KB Output is correct
11 Correct 5 ms 4992 KB Output is correct
12 Correct 5 ms 4992 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 4992 KB Output is correct
2 Correct 5 ms 4992 KB Output is correct
3 Correct 5 ms 4992 KB Output is correct
4 Correct 6 ms 4992 KB Output is correct
5 Correct 5 ms 4992 KB Output is correct
6 Correct 5 ms 4992 KB Output is correct
7 Correct 5 ms 4992 KB Output is correct
8 Correct 6 ms 4992 KB Output is correct
9 Correct 5 ms 4992 KB Output is correct
10 Correct 6 ms 4992 KB Output is correct
11 Correct 5 ms 4992 KB Output is correct
12 Correct 5 ms 4992 KB Output is correct
13 Correct 5 ms 4992 KB Output is correct
14 Correct 5 ms 4992 KB Output is correct
15 Correct 6 ms 4992 KB Output is correct
16 Correct 6 ms 4992 KB Output is correct
17 Correct 5 ms 4992 KB Output is correct
18 Correct 5 ms 4992 KB Output is correct
19 Correct 6 ms 4992 KB Output is correct
20 Correct 6 ms 5120 KB Output is correct
21 Correct 5 ms 4992 KB Output is correct
22 Correct 6 ms 5120 KB Output is correct

Subtask #3
29.0 / 29.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 4992 KB Output is correct
2 Correct 5 ms 4992 KB Output is correct
3 Correct 5 ms 4992 KB Output is correct
4 Correct 6 ms 4992 KB Output is correct
5 Correct 5 ms 4992 KB Output is correct
6 Correct 5 ms 4992 KB Output is correct
7 Correct 5 ms 4992 KB Output is correct
8 Correct 6 ms 4992 KB Output is correct
9 Correct 5 ms 4992 KB Output is correct
10 Correct 6 ms 4992 KB Output is correct
11 Correct 5 ms 4992 KB Output is correct
12 Correct 5 ms 4992 KB Output is correct
13 Correct 5 ms 4992 KB Output is correct
14 Correct 5 ms 4992 KB Output is correct
15 Correct 6 ms 4992 KB Output is correct
16 Correct 6 ms 4992 KB Output is correct
17 Correct 5 ms 4992 KB Output is correct
18 Correct 5 ms 4992 KB Output is correct
19 Correct 6 ms 4992 KB Output is correct
20 Correct 6 ms 5120 KB Output is correct
21 Correct 5 ms 4992 KB Output is correct
22 Correct 6 ms 5120 KB Output is correct
23 Correct 10 ms 5248 KB Output is correct
24 Correct 9 ms 5248 KB Output is correct
25 Correct 9 ms 5248 KB Output is correct
26 Correct 13 ms 5504 KB Output is correct
27 Correct 14 ms 5504 KB Output is correct
28 Correct 14 ms 6144 KB Output is correct
29 Correct 12 ms 5760 KB Output is correct
30 Correct 13 ms 5760 KB Output is correct
31 Correct 14 ms 6784 KB Output is correct

Subtask #4
43.0 / 43.0

# Verdict Execution time Memory Grader output
1 Correct 5 ms 4992 KB Output is correct
2 Correct 5 ms 4992 KB Output is correct
3 Correct 5 ms 4992 KB Output is correct
4 Correct 6 ms 4992 KB Output is correct
5 Correct 5 ms 4992 KB Output is correct
6 Correct 5 ms 4992 KB Output is correct
7 Correct 5 ms 4992 KB Output is correct
8 Correct 6 ms 4992 KB Output is correct
9 Correct 5 ms 4992 KB Output is correct
10 Correct 6 ms 4992 KB Output is correct
11 Correct 5 ms 4992 KB Output is correct
12 Correct 5 ms 4992 KB Output is correct
13 Correct 5 ms 4992 KB Output is correct
14 Correct 5 ms 4992 KB Output is correct
15 Correct 6 ms 4992 KB Output is correct
16 Correct 6 ms 4992 KB Output is correct
17 Correct 5 ms 4992 KB Output is correct
18 Correct 5 ms 4992 KB Output is correct
19 Correct 6 ms 4992 KB Output is correct
20 Correct 6 ms 5120 KB Output is correct
21 Correct 5 ms 4992 KB Output is correct
22 Correct 6 ms 5120 KB Output is correct
23 Correct 10 ms 5248 KB Output is correct
24 Correct 9 ms 5248 KB Output is correct
25 Correct 9 ms 5248 KB Output is correct
26 Correct 13 ms 5504 KB Output is correct
27 Correct 14 ms 5504 KB Output is correct
28 Correct 14 ms 6144 KB Output is correct
29 Correct 12 ms 5760 KB Output is correct
30 Correct 13 ms 5760 KB Output is correct
31 Correct 14 ms 6784 KB Output is correct
32 Correct 56 ms 7772 KB Output is correct
33 Correct 57 ms 7672 KB Output is correct
34 Correct 50 ms 7672 KB Output is correct
35 Correct 271 ms 15608 KB Output is correct
36 Correct 274 ms 15864 KB Output is correct
37 Correct 269 ms 15608 KB Output is correct
38 Correct 212 ms 24788 KB Output is correct
39 Correct 214 ms 20032 KB Output is correct
40 Correct 228 ms 17908 KB Output is correct
41 Correct 294 ms 30952 KB Output is correct