Submission #1128513

#	Time	Username	Problem	Language	Result	Execution time	Memory
1128513		cbnhtmanh	Election Campaign (JOI15_election_campaign)	C++20	100 / 100	156 ms	41276 KiB

election_campaign

#include <bits/stdc++.h>
#define fi(i, a, b) for( int i = a; i <= b; i++ )
#define fid(i, a, b) for( int i = a; i >= b; i-- )
#define getbit(x, i) ((x>>i)&1)
#define ll long long
#define pb push_back
#define pii pair<int,int>
#define pli pair<ll,int>
#define pll pair<ll,ll>
#define st first
#define nd second
#define mp make_pair
#define HTManh ""
#define maxn 100009
#define endl '\n'
using namespace std;

int n;
vector<int> a[100009];
int m;
struct dl
{
    int u, v;
    int c;
} tv[100009];

bool check()
{
    fi(u,1,n) for(int v: a[u]) if (u < v && u != v-1) return 0;
    return 1;
}

vector<pii> truyvan[100009];
ll mx[100009];

void sub23()
{
    //cout << "gay" << endl;
    fi(i,1,m)
    {
        int u = tv[i].u, v = tv[i].v, c = tv[i].c;
        if (u > v) swap(u, v);
        truyvan[v].pb({u, c});
    }
    fi(i,1,n)
    {
        ll gt = 0;
        for(pii tg: truyvan[i])
        {
            gt = max(gt, mx[tg.st - 1] + tg.nd);
        }
        mx[i] = max(mx[i-1], gt);
    }
    cout << mx[n] << endl;
}

int h[100009];
int euler[200009], cnt;
int dau[200009];

void dfs(int u, int pre = 0)
{
    euler[++cnt] = u;
    dau[u] = cnt;
    for(int v: a[u])
    {
        if (v == pre) continue;
        h[v] = h[u] + 1;
        dfs(v,u);
        euler[++cnt] = u;
    }
}

int anc[200009][21];

void build_lca()
{
    fi(i,1,cnt) anc[i][0] = euler[i];
    fi(k,1,__lg(cnt))
    {
        fi(i,1,cnt-(1<<k)+1)
        {
            anc[i][k] = (h[anc[i][k-1]] < h[anc[i+(1<<(k-1))][k-1]]) ? anc[i][k-1] : anc[i+(1<<(k-1))][k-1];
        }
    }
}

int lca(int u, int v)
{
    if (dau[u] > dau[v]) swap(u,v);
    int k = __lg(dau[v]-dau[u]+1);
    return (h[anc[dau[u]][k]] < h[anc[dau[v]-(1<<k)+1][k]] ? anc[dau[u]][k] : anc[dau[v]-(1<<k)+1][k]);
}

int dis(int u, int v)
{
    return h[u] + h[v] - 2*h[lca(u, v)];
}

void sub1()
{
    dfs(1);
    build_lca();
    ll res = 0;
    fi(x,1,(1<<m)-1)
    {
        bool flag = 1;
        fi(i,1,m) if (getbit(x,(i-1)))
        {
            fi(j,1,i-1) if (getbit(x,(j-1)))
            {
                int dinh1 = lca(tv[i].u, tv[i].v);
                int dinh2 = lca(tv[j].u, tv[j].v);
                if (dis(tv[i].u, tv[i].v) == dis(tv[i].u, dinh2) + dis(tv[i].v, dinh2)) flag = 0;
                if (dis(tv[j].u, tv[j].v) == dis(tv[j].u, dinh1) + dis(tv[j].v, dinh1)) flag = 0;
            }
        }
        if (!flag) continue;
        ll kq = 0;
        fi(i,1,m) if (getbit(x,(i-1))) kq += tv[i].c;
        res = max(res, kq);
    }
    cout << res << endl;
}

vector<pair<pii, int>> query[100009];

int st[100009], ed[100009], dem;

void dfs2(int u, int pre = 0)
{
    st[u] = ++dem;
    for(int v: a[u])
    {
        if (v == pre) continue;
        dfs2(v,u);
    }
    ed[u] = dem;
}

ll dp[100009][2];

ll bit[100009][2];

void update(int tt, int vt, int gt)
{
    while (vt <= n)
    {
        bit[vt][tt] += gt;
        vt += vt & -vt;
    }
}

ll get(int tt, int vt)
{
    ll s = 0;
    while(vt > 0)
    {
        s += bit[vt][tt];
        vt -= vt & -vt;
    }
    return s;
}

void solve(int u, int pre = 0)
{
    for(int v: a[u])
    {
        if (v == pre) continue;
        solve(v,u);
        dp[u][0] += max(dp[v][0], dp[v][1]);
    }
    update(0,st[u],dp[u][0]); update(0,ed[u]+1,-dp[u][0]);

    for(pair<pii, int> tg: query[u])
    {
        int x = tg.st.st, y = tg.st.nd, gt = tg.nd;
        if (h[x] > h[y]) swap(x,y);

        //cout << x << " " << y << " " << gt << endl;

        if (x == u)
        {
            dp[u][1] = max(dp[u][1], get(0, st[y]) - get(1, st[y]) + gt);
        }
        else
        {
            dp[u][1] = max(dp[u][1], get(0, st[x]) - get(1, st[x]) + get(0, st[y]) - get(1, st[y]) + gt - dp[u][0]);
        }
    }
    ll gt = max(dp[u][0], dp[u][1]);
    update(1,st[u],gt); update(1,ed[u]+1,-gt);
}

void subac()
{
    dfs(1);
    build_lca();
    dfs2(1);
    fi(i,1,m)
    {
        int dinh = lca(tv[i].u, tv[i].v);
        query[dinh].pb({{tv[i].u, tv[i].v}, tv[i].c});
    }
    solve(1);
    cout << max(dp[1][0], dp[1][1]) << endl;
}

int main()
{
	ios_base::sync_with_stdio(0);
	cin.tie(NULL); cout.tie(NULL);
	if (fopen(HTManh".inp", "r"))
    {
        freopen(HTManh".inp", "r", stdin);
        freopen(HTManh".out", "w", stdout);
    }

    cin >> n;
    fi(i,1,n-1)
    {
        int x, y;
        cin >> x >> y;
        a[x].pb(y);
        a[y].pb(x);
    }
    cin >> m;
    fi(i,1,m) cin >> tv[i].u >> tv[i].v >> tv[i].c;

    if (check()) sub23();
    else
    {
        if (m <= 15) sub1();
        else
        {
            subac();
        }
    }
}

Compilation message (stderr)

election_campaign.cpp: In function 'int main()':
election_campaign.cpp:215:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  215 |         freopen(HTManh".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~
election_campaign.cpp:216:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  216 |         freopen(HTManh".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