Submission #99780

#	Time	Username	Problem	Language	Result	Execution time	Memory
99780		PeppaPig	구슬과 끈 (APIO14_beads)	C++14	0 / 100	6 ms	4992 KiB

beads

#include <bits/stdc++.h>

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

using namespace std;

const int N = 2e5+5;

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);

    int mx = -1e9;
    vector<int> V, W, M;
    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][2] + v.y));
        dp[u][0] += M.back();
    }
    dp[u][1] = dp[u][2] = dp[u][3] = -1e9;

    for(int i = 0; i < V.size(); i++) {
        dp[u][1] = max(dp[u][1], dp[u][0] - M[i] + dp[V[i]][1] + W[i] + mx);
        mx = max(mx, - M[i] + dp[V[i]][0] + W[i]);
    }
    mx = -1e9;
    for(int i = V.size() - 1; ~i; i--) {
        dp[u][1] = max(dp[u][1], dp[u][0] - M[i] + dp[V[i]][1] + W[i] + mx);
        mx = max(mx, - M[i] + dp[V[i]][0] + W[i]);
    }
    mx = -1e9;
    for(int i = 0; i < V.size(); i++) {
        dp[u][1] = max(dp[u][1], dp[u][0] - M[i] + dp[V[i]][0] + W[i] + mx);
        mx = max(mx, - M[i] + dp[V[i]][0] + W[i]);
    }

    for(int i = 0; i < V.size(); i++) {
        dp[u][2] = max(dp[u][2], 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]][1] + W[i]);
    }

    for(int i = 0; i < V.size(); i++) 
        dp[u][1] = max(dp[u][1], dp[u][0] - M[i] + max(dp[V[i]][1], dp[V[i]][3]));
}

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][1]));

    return 0;
}

Compilation message (stderr)

beads.cpp: In function 'void dfs(int, int)':
beads.cpp:26:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 0; i < V.size(); i++) {
                    ~~^~~~~~~~~~
beads.cpp:36:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 0; i < V.size(); i++) {
                    ~~^~~~~~~~~~
beads.cpp:41:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 0; i < V.size(); i++) {
                    ~~^~~~~~~~~~
beads.cpp:46:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i = 0; i < V.size(); i++) 
                    ~~^~~~~~~~~~
beads.cpp: In function 'int main()':
beads.cpp:51:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d", &n);
     ~~~~~^~~~~~~~~~
beads.cpp:53:14: 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: 0 / 13
• Subtask 2: 0 / 15
• Subtask 3: 0 / 29
• Subtask 4: 0 / 43