Submission #433573

#	Time	Username	Problem	Language	Result	Execution time	Memory
433573		cpp219	Election Campaign (JOI15_election_campaign)	C++14	100 / 100	486 ms	34244 KiB

election_campaign

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

#include <bits/stdc++.h>
#define ll int
#define ld long double
#define fs first
#define sc second
using namespace std;
const ll N = 1e5 + 9;
const ll mod = 1e9 + 7;
const ll Log2 = 20;
typedef pair<ll,ll> LL;
vector<ll> g[N],Q[N];
ll n,m,x,y,All[N],dp[N];

struct plan{
    ll x,y,cost;
};
plan q[N];

ll par[N][Log2],d[N],ans,child[N];
void DFS(ll u,ll p){
    child[u] = 1;
    for (ll i = 1;i < Log2;i++) if ((1 << i) <= d[u])
        par[u][i] = par[par[u][i - 1]][i - 1];
    for (auto i : g[u]){
        if (i == p) continue;
        par[i][0] = u; d[i] = d[u] + 1; DFS(i,u);
        child[u] += child[i];
    }
}

ll LCA(ll u,ll v){
    if (d[u] > d[v]) swap(u,v);
    for (ll i = Log2 - 1;i >= 0;i--) if ((1 << i) <= d[v] && d[par[v][i]] >= d[u])
        v = par[v][i];
    if (u == v) return u;
    for (ll i = Log2 - 1;i >= 0;i--) if (par[v][i] != par[u][i])
        v = par[v][i],u = par[u][i];
    return par[u][0];
}

ll st[4*N];

void upd(ll id,ll l,ll r,ll u,ll val){
    if (u < l||r < u) return;
    if (l == r){
        st[id] += val; return;
    }
    ll mid = (l + r)/2;
    upd(id*2,l,mid,u,val); upd(id*2 + 1,mid + 1,r,u,val);
    st[id] = st[id*2] + st[id*2 + 1];
}

ll Get(ll id,ll l,ll r,ll u,ll v){
    if (v < l||r < u) return 0;
    if (u <= l&&r <= v) return st[id];
    ll mid = (l + r)/2;
    return Get(id*2,l,mid,u,v) + Get(id*2 + 1,mid + 1,r,u,v);
}

ll pos[N],Real[N],chain[N],head[N],nTime = 1,cur = 1;

void DFShld(ll u,ll p){
    pos[u] = nTime; Real[nTime] = u; nTime++;
    if (!head[cur]) head[cur] = u; chain[u] = cur;
    LL s = {0,0};
    for (auto i : g[u]){
        if (i == p) continue;
        s = max(s,{child[i],i});
    }
    if (s.sc) DFShld(s.sc,u);
    for (auto i : g[u]){
        if (i == p || i == s.sc) continue;
        cur++; DFShld(i,u);
    }
}

ll hld(ll u,ll v){
    /// u is par of v
    ll res = 0;
    while(chain[u] != chain[v]){
        ll nxt = head[chain[v]];
        res += Get(1,1,n,pos[nxt],pos[v]);
        v = par[nxt][0];
    }

    res += Get(1,1,n,pos[u],pos[v]); return res;
}

void f(ll u){
    for (auto i : g[u]) if (d[i] > d[u]) f(i),All[u] += dp[i];
    upd(1,1,n,pos[u],All[u]); dp[u] = All[u];

    for (auto i : Q[u]){
        x = q[i].x; y = q[i].y; ll cost = q[i].cost;
        dp[u] = max(dp[u],hld(u,x) + hld(u,y) - All[u] + cost);
    }

    upd(1,1,n,pos[u],-dp[u]); ans = max(ans,dp[u]);

}

int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0), cout.tie(0);
    #define task "test"
    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;
        g[x].push_back(y); g[y].push_back(x);
    }
    DFS(1,0); DFShld(1,0);
    cin>>m;
    for (ll i = 1;i <= m;i++){
        cin>>q[i].x>>q[i].y>>q[i].cost;
        if (d[q[i].x] > d[q[i].y]) swap(q[i].x,q[i].y);
        ll now = LCA(q[i].x,q[i].y);
        Q[now].push_back(i);

    }
    f(1); cout<<ans;
}

Compilation message (stderr)

election_campaign.cpp:1: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
    1 | #pragma GCC optimization "O2"
      | 
election_campaign.cpp:2: warning: ignoring '#pragma GCC optimization' [-Wunknown-pragmas]
    2 | #pragma GCC optimization "unroll-loop"
      | 
election_campaign.cpp: In function 'void DFShld(int, int)':
election_campaign.cpp:68:5: warning: this 'if' clause does not guard... [-Wmisleading-indentation]
   68 |     if (!head[cur]) head[cur] = u; chain[u] = cur;
      |     ^~
election_campaign.cpp:68:36: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'if'
   68 |     if (!head[cur]) head[cur] = u; chain[u] = cur;
      |                                    ^~~~~
election_campaign.cpp: In function 'int main()':
election_campaign.cpp:111:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  111 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
election_campaign.cpp:112:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  112 |         freopen(task".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 5 / 5
• Subtask 3: 5 / 5
• Subtask 4: 30 / 30
• Subtask 5: 10 / 10
• Subtask 6: 40 / 40