Submission #434855

#	Time	Username	Problem	Language	Result	Execution time	Memory
434855		cpp219	Beads and wires (APIO14_beads)	C++14	28 / 100	1 ms	484 KiB

beads

#pragma GCC optimization O2
#pragma GCC optimization "unroll-loop"
#pragma target ("avx2")

#include <bits/stdc++.h>
#define ll int
#define ld long double
#define fs first
#define sc second
using namespace std;
typedef pair<ll,ll> LL;
const ll N = 1e3 + 9;
const ll inf = 1e9 + 7;
vector<LL> g[N];
ll n,x,y,w,dp[N][2],All[N],ans;

void DFS(ll u,ll p){
    ll child = 0;
    for (auto i : g[u]) if (i.fs != p) DFS(i.fs,u),child++;
    dp[u][0] = dp[u][1] = 0;
    if (!child) dp[u][1] = -inf;
    for (auto i : g[u]){
        ll v = i.fs,cost = i.sc;
        if (v == p) continue;
        dp[u][0] += max(dp[v][1] + cost,dp[v][0]);
        All[u] += dp[v][1];
    }
    for (auto i : g[u]){
        ll v = i.fs,cost = i.sc;
        if (v == p) continue;
        ll now = dp[u][0] - max(dp[v][1] + cost,dp[v][0]) + dp[v][0] + cost;
        dp[u][1] = max(dp[u][1],now);
    }
}

int main(){
    ios_base::sync_with_stdio(NULL); cin.tie(0); cout.tie(0);
    #define task "tst"
    if (fopen(task".INP","r")){
        freopen(task".INP","r",stdin);
        //freopen(task".OUT","w",stdout);
    }
    cin>>n;
    for (ll i = 1;i < n;i++){
        cin>>x>>y>>w;
        g[x].push_back({y,w}); g[y].push_back({x,w});
    }
    for (ll i = 1;i <= n;i++){
        DFS(i,0);
        ans = max(ans,dp[i][0]); //cout<<dp[i][0]; return 0;
    }
    cout<<ans;
}

Compilation message (stderr)

beads.cpp:1: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
    1 | #pragma GCC optimization O2
      | 
beads.cpp:2: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
    2 | #pragma GCC optimization "unroll-loop"
      | 
beads.cpp:3: warning: ignoring '#pragma target ' [-Wunknown-pragmas]
    3 | #pragma target ("avx2")
      | 
beads.cpp: In function 'int main()':
beads.cpp:40:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   40 |         freopen(task".INP","r",stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 13 / 13
• Subtask 2: 15 / 15
• Subtask 3: 0 / 29
• Subtask 4: 0 / 43