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Submission #581206

# Submission time Handle Problem Language Result Execution time Memory
581206 2022-06-22T11:28:08 Z qwerasdfzxcl Beads and wires (APIO14_beads) C++14
100 / 100
 254 ms 24988 KB 
#include <bits/stdc++.h>

typedef long long ll;
using namespace std;
vector<pair<int, int>> adj[200200];
int dp[200200][2], dp2[200200][2], par[200200], paw[200200];

void dfs(int s, int pa = -1, int w0 = 0){
    int tmp = -1e9;
    dp[s][0] = 0;
    par[s] = pa;
    paw[s] = w0;
    for (auto &[v, w]:adj[s]) if (v!=pa){
        dfs(v, s, w);
        tmp = max(tmp, dp[v][0] + w - dp[v][1]);
        dp[s][0] += dp[v][1];
    }

    if (w0+tmp>0) dp[s][1] = dp[s][0] + w0 + tmp;
    else dp[s][1] = dp[s][0];
    //if (C.size()>=2) dp[s][0] = max(dp[s][0], dp[s][0] + C[0] + C[1]);

    //printf("%d: %d %d\n", s, dp[s][0], dp[s][1]);
}

void dfs2(int s, int pa  = -1, int w0 = 0, int sum = 0, int mx = 0){
    if (pa!=-1){
        dp2[s][0] = sum - dp[s][1];

        if (w0 + mx>0) dp2[s][1] = dp2[s][0] + w0 + mx;
        else dp2[s][1] = dp2[s][0];
    }

    int ns = 0;
    vector<int> nmx = {-1000000000, -1000000000};
    for (auto &[v, w]:adj[s]) if (v!=pa){
        ns += dp[v][1];
        nmx.push_back(dp[v][0]+w - dp[v][1]);
    }
    if (pa!=-1){
        ns += dp2[s][1];
        nmx.push_back(dp2[s][0]+w0 - dp2[s][1]);
    }

    sort(nmx.begin(), nmx.end(), greater<int>());

    for (auto &[v, w]:adj[s]) if (v!=pa){
        if (nmx[0]!=dp[v][0]+w-dp[v][1]) dfs2(v, s, w, ns, nmx[0]);
        else dfs2(v, s, w, ns, nmx[1]);
    }
}

int calc(int s){
    int ret1 = 0, ret2 = 0;
    for (auto &[v, w]:adj[s]) if (v!=par[s]){
        ret1 += dp[v][1];
    }
    if (par[s]!=-1) ret1 += dp2[s][1];

    if (adj[s].size()<2) return ret1;

    vector<int> V;
    for (auto &[v, w]:adj[s]) if (v!=par[s]) V.push_back(dp[v][0]+w - dp[v][1]);
    if (par[s]!=-1) V.push_back(dp2[s][0]+paw[s] - dp2[s][1]);
    sort(V.begin(), V.end(), greater<int>());

    ret2 = ret1 + V[0] + V[1];
    return max(ret1, ret2);
}

int main(){
    int n;
    scanf("%d", &n);
    for (int i=0;i<n-1;i++){
        int x, y, z;
        scanf("%d %d %d", &x, &y, &z);
        adj[x].emplace_back(y, z);
        adj[y].emplace_back(x, z);
    }

    dfs(1);
    dfs2(1);

    //for (int i=1;i<=n;i++) printf("%d: %d %d\n", i, dp[i][0], dp[i][1]);
    //for (int i=1;i<=n;i++) printf("%d: %d %d\n", i, dp2[i][0], dp2[i][1]);


    int ans = 0;
    for (int i=1;i<=n;i++) ans = max(ans, calc(i));
    printf("%d\n", ans);
    return 0;
}

Compilation message

beads.cpp: In function 'void dfs(int, int, int)':
beads.cpp:13:16: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   13 |     for (auto &[v, w]:adj[s]) if (v!=pa){
      |                ^
beads.cpp: In function 'void dfs2(int, int, int, int, int)':
beads.cpp:36:16: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   36 |     for (auto &[v, w]:adj[s]) if (v!=pa){
      |                ^
beads.cpp:47:16: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   47 |     for (auto &[v, w]:adj[s]) if (v!=pa){
      |                ^
beads.cpp: In function 'int calc(int)':
beads.cpp:55:16: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   55 |     for (auto &[v, w]:adj[s]) if (v!=par[s]){
      |                ^
beads.cpp:63:16: warning: structured bindings only available with '-std=c++17' or '-std=gnu++17'
   63 |     for (auto &[v, w]:adj[s]) if (v!=par[s]) V.push_back(dp[v][0]+w - dp[v][1]);
      |                ^
beads.cpp: In function 'int main()':
beads.cpp:73:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   73 |     scanf("%d", &n);
      |     ~~~~~^~~~~~~~~~
beads.cpp:76:14: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   76 |         scanf("%d %d %d", &x, &y, &z);
      |         ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~

Subtask #1
13.0 / 13.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 5008 KB Output is correct
2 Correct 3 ms 4948 KB Output is correct
3 Correct 3 ms 5008 KB Output is correct
4 Correct 3 ms 4948 KB Output is correct
5 Correct 3 ms 4948 KB Output is correct
6 Correct 4 ms 4948 KB Output is correct
7 Correct 2 ms 4948 KB Output is correct
8 Correct 3 ms 4948 KB Output is correct
9 Correct 3 ms 5008 KB Output is correct
10 Correct 3 ms 5008 KB Output is correct
11 Correct 3 ms 4948 KB Output is correct
12 Correct 3 ms 4948 KB Output is correct

Subtask #2
15.0 / 15.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 5008 KB Output is correct
2 Correct 3 ms 4948 KB Output is correct
3 Correct 3 ms 5008 KB Output is correct
4 Correct 3 ms 4948 KB Output is correct
5 Correct 3 ms 4948 KB Output is correct
6 Correct 4 ms 4948 KB Output is correct
7 Correct 2 ms 4948 KB Output is correct
8 Correct 3 ms 4948 KB Output is correct
9 Correct 3 ms 5008 KB Output is correct
10 Correct 3 ms 5008 KB Output is correct
11 Correct 3 ms 4948 KB Output is correct
12 Correct 3 ms 4948 KB Output is correct
13 Correct 4 ms 4948 KB Output is correct
14 Correct 4 ms 5008 KB Output is correct
15 Correct 3 ms 4948 KB Output is correct
16 Correct 3 ms 4948 KB Output is correct
17 Correct 4 ms 4948 KB Output is correct
18 Correct 3 ms 4948 KB Output is correct
19 Correct 3 ms 5004 KB Output is correct
20 Correct 3 ms 4948 KB Output is correct
21 Correct 3 ms 4948 KB Output is correct
22 Correct 4 ms 4956 KB Output is correct

Subtask #3
29.0 / 29.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 5008 KB Output is correct
2 Correct 3 ms 4948 KB Output is correct
3 Correct 3 ms 5008 KB Output is correct
4 Correct 3 ms 4948 KB Output is correct
5 Correct 3 ms 4948 KB Output is correct
6 Correct 4 ms 4948 KB Output is correct
7 Correct 2 ms 4948 KB Output is correct
8 Correct 3 ms 4948 KB Output is correct
9 Correct 3 ms 5008 KB Output is correct
10 Correct 3 ms 5008 KB Output is correct
11 Correct 3 ms 4948 KB Output is correct
12 Correct 3 ms 4948 KB Output is correct
13 Correct 4 ms 4948 KB Output is correct
14 Correct 4 ms 5008 KB Output is correct
15 Correct 3 ms 4948 KB Output is correct
16 Correct 3 ms 4948 KB Output is correct
17 Correct 4 ms 4948 KB Output is correct
18 Correct 3 ms 4948 KB Output is correct
19 Correct 3 ms 5004 KB Output is correct
20 Correct 3 ms 4948 KB Output is correct
21 Correct 3 ms 4948 KB Output is correct
22 Correct 4 ms 4956 KB Output is correct
23 Correct 7 ms 5404 KB Output is correct
24 Correct 6 ms 5332 KB Output is correct
25 Correct 7 ms 5332 KB Output is correct
26 Correct 10 ms 5588 KB Output is correct
27 Correct 10 ms 5588 KB Output is correct
28 Correct 9 ms 5740 KB Output is correct
29 Correct 8 ms 5700 KB Output is correct
30 Correct 8 ms 5712 KB Output is correct
31 Correct 9 ms 6336 KB Output is correct

Subtask #4
43.0 / 43.0

# Verdict Execution time Memory Grader output
1 Correct 3 ms 5008 KB Output is correct
2 Correct 3 ms 4948 KB Output is correct
3 Correct 3 ms 5008 KB Output is correct
4 Correct 3 ms 4948 KB Output is correct
5 Correct 3 ms 4948 KB Output is correct
6 Correct 4 ms 4948 KB Output is correct
7 Correct 2 ms 4948 KB Output is correct
8 Correct 3 ms 4948 KB Output is correct
9 Correct 3 ms 5008 KB Output is correct
10 Correct 3 ms 5008 KB Output is correct
11 Correct 3 ms 4948 KB Output is correct
12 Correct 3 ms 4948 KB Output is correct
13 Correct 4 ms 4948 KB Output is correct
14 Correct 4 ms 5008 KB Output is correct
15 Correct 3 ms 4948 KB Output is correct
16 Correct 3 ms 4948 KB Output is correct
17 Correct 4 ms 4948 KB Output is correct
18 Correct 3 ms 4948 KB Output is correct
19 Correct 3 ms 5004 KB Output is correct
20 Correct 3 ms 4948 KB Output is correct
21 Correct 3 ms 4948 KB Output is correct
22 Correct 4 ms 4956 KB Output is correct
23 Correct 7 ms 5404 KB Output is correct
24 Correct 6 ms 5332 KB Output is correct
25 Correct 7 ms 5332 KB Output is correct
26 Correct 10 ms 5588 KB Output is correct
27 Correct 10 ms 5588 KB Output is correct
28 Correct 9 ms 5740 KB Output is correct
29 Correct 8 ms 5700 KB Output is correct
30 Correct 8 ms 5712 KB Output is correct
31 Correct 9 ms 6336 KB Output is correct
32 Correct 39 ms 8036 KB Output is correct
33 Correct 39 ms 8012 KB Output is correct
34 Correct 60 ms 8104 KB Output is correct
35 Correct 254 ms 17164 KB Output is correct
36 Correct 248 ms 17172 KB Output is correct
37 Correct 254 ms 17152 KB Output is correct
38 Correct 155 ms 19228 KB Output is correct
39 Correct 145 ms 18688 KB Output is correct
40 Correct 152 ms 18380 KB Output is correct
41 Correct 235 ms 24988 KB Output is correct