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답안 #581058

# 제출 시각 아이디 문제 언어 결과 실행 시간 메모리
581058 2022-06-22T08:52:18 Z 박상훈(#8359) 구슬과 끈 (APIO14_beads) C++17
100 / 100
 285 ms 25040 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 '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

# 결과 실행 시간 메모리 Grader output
1 Correct 3 ms 4948 KB Output is correct
2 Correct 5 ms 4948 KB Output is correct
3 Correct 4 ms 5004 KB Output is correct
4 Correct 3 ms 4948 KB Output is correct
5 Correct 5 ms 5008 KB Output is correct
6 Correct 4 ms 5028 KB Output is correct
7 Correct 3 ms 4948 KB Output is correct
8 Correct 3 ms 5008 KB Output is correct
9 Correct 3 ms 4948 KB Output is correct
10 Correct 4 ms 5004 KB Output is correct
11 Correct 4 ms 5004 KB Output is correct
12 Correct 3 ms 4948 KB Output is correct

Subtask #2
15.0 / 15.0

# 결과 실행 시간 메모리 Grader output
1 Correct 3 ms 4948 KB Output is correct
2 Correct 5 ms 4948 KB Output is correct
3 Correct 4 ms 5004 KB Output is correct
4 Correct 3 ms 4948 KB Output is correct
5 Correct 5 ms 5008 KB Output is correct
6 Correct 4 ms 5028 KB Output is correct
7 Correct 3 ms 4948 KB Output is correct
8 Correct 3 ms 5008 KB Output is correct
9 Correct 3 ms 4948 KB Output is correct
10 Correct 4 ms 5004 KB Output is correct
11 Correct 4 ms 5004 KB Output is correct
12 Correct 3 ms 4948 KB Output is correct
13 Correct 4 ms 4948 KB Output is correct
14 Correct 3 ms 4948 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 4 ms 5004 KB Output is correct
19 Correct 4 ms 4948 KB Output is correct
20 Correct 4 ms 4948 KB Output is correct
21 Correct 4 ms 4948 KB Output is correct
22 Correct 3 ms 4948 KB Output is correct

Subtask #3
29.0 / 29.0

# 결과 실행 시간 메모리 Grader output
1 Correct 3 ms 4948 KB Output is correct
2 Correct 5 ms 4948 KB Output is correct
3 Correct 4 ms 5004 KB Output is correct
4 Correct 3 ms 4948 KB Output is correct
5 Correct 5 ms 5008 KB Output is correct
6 Correct 4 ms 5028 KB Output is correct
7 Correct 3 ms 4948 KB Output is correct
8 Correct 3 ms 5008 KB Output is correct
9 Correct 3 ms 4948 KB Output is correct
10 Correct 4 ms 5004 KB Output is correct
11 Correct 4 ms 5004 KB Output is correct
12 Correct 3 ms 4948 KB Output is correct
13 Correct 4 ms 4948 KB Output is correct
14 Correct 3 ms 4948 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 4 ms 5004 KB Output is correct
19 Correct 4 ms 4948 KB Output is correct
20 Correct 4 ms 4948 KB Output is correct
21 Correct 4 ms 4948 KB Output is correct
22 Correct 3 ms 4948 KB Output is correct
23 Correct 8 ms 5280 KB Output is correct
24 Correct 6 ms 5240 KB Output is correct
25 Correct 6 ms 5332 KB Output is correct
26 Correct 13 ms 5588 KB Output is correct
27 Correct 9 ms 5608 KB Output is correct
28 Correct 8 ms 5716 KB Output is correct
29 Correct 7 ms 5588 KB Output is correct
30 Correct 8 ms 5636 KB Output is correct
31 Correct 9 ms 6228 KB Output is correct

Subtask #4
43.0 / 43.0

# 결과 실행 시간 메모리 Grader output
1 Correct 3 ms 4948 KB Output is correct
2 Correct 5 ms 4948 KB Output is correct
3 Correct 4 ms 5004 KB Output is correct
4 Correct 3 ms 4948 KB Output is correct
5 Correct 5 ms 5008 KB Output is correct
6 Correct 4 ms 5028 KB Output is correct
7 Correct 3 ms 4948 KB Output is correct
8 Correct 3 ms 5008 KB Output is correct
9 Correct 3 ms 4948 KB Output is correct
10 Correct 4 ms 5004 KB Output is correct
11 Correct 4 ms 5004 KB Output is correct
12 Correct 3 ms 4948 KB Output is correct
13 Correct 4 ms 4948 KB Output is correct
14 Correct 3 ms 4948 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 4 ms 5004 KB Output is correct
19 Correct 4 ms 4948 KB Output is correct
20 Correct 4 ms 4948 KB Output is correct
21 Correct 4 ms 4948 KB Output is correct
22 Correct 3 ms 4948 KB Output is correct
23 Correct 8 ms 5280 KB Output is correct
24 Correct 6 ms 5240 KB Output is correct
25 Correct 6 ms 5332 KB Output is correct
26 Correct 13 ms 5588 KB Output is correct
27 Correct 9 ms 5608 KB Output is correct
28 Correct 8 ms 5716 KB Output is correct
29 Correct 7 ms 5588 KB Output is correct
30 Correct 8 ms 5636 KB Output is correct
31 Correct 9 ms 6228 KB Output is correct
32 Correct 39 ms 8040 KB Output is correct
33 Correct 44 ms 8052 KB Output is correct
34 Correct 45 ms 8044 KB Output is correct
35 Correct 261 ms 17248 KB Output is correct
36 Correct 285 ms 17168 KB Output is correct
37 Correct 233 ms 17080 KB Output is correct
38 Correct 158 ms 19220 KB Output is correct
39 Correct 152 ms 18596 KB Output is correct
40 Correct 173 ms 18388 KB Output is correct
41 Correct 225 ms 25040 KB Output is correct