Submission #952745

#	Time	Username	Problem	Language	Result	Execution time	Memory
952745		gaga999	Mountains and Valleys (CCO20_day1problem3)	C++17	0 / 25	115 ms	225552 KiB

Main

// #pragma GCC optimize("Ofast,no-stack-protector")
// #pragma GCC optimize("O3,unroll-loops")
// #pragma GCC target("avx,avx2,bmi,bmi2,lzcnt,popcnt")
#include <bits/stdc++.h>
#define lowbit(x) ((x) & -(x))
#define ml(a, b) ((1ll * (a) * (b)) % M)
#define tml(a, b) (a) = ((1ll * (a) * (b)) % M)
#define ad(a, b) ((0ll + (a) + (b)) % M)
#define tad(a, b) (a) = ((0ll + (a) + (b)) % M)
#define mi(a, b) ((0ll + M + (a) - (b)) % M)
#define tmi(a, b) (a) = ((0ll + M + (a) - (b)) % M)
#define tmin(a, b) (a) = min((a), (b))
#define tmax(a, b) (a) = max((a), (b))
#define iter(a) (a).begin(), (a).end()
#define riter(a) (a).rbegin(), (a).rend()
#define init(a, b) memset((a), (b), sizeof(a))
#define cpy(a, b) memcpy((a), (b), sizeof(a))
#define uni(a) a.resize(unique(iter(a)) - a.begin())
#define size(x) (int)x.size()
#define pb emplace_back
#define mpr make_pair
#define ls(i) ((i) << 1)
#define rs(i) ((i) << 1 | 1)
#define INF 0x3f3f3f3f
#define NIF 0xc0c0c0c0
#define eps 1e-9
#define F first
#define S second
#define AC cin.tie(0)->sync_with_stdio(0)
using namespace std;
typedef long long llt;
typedef pair<int, int> pii;
typedef pair<double, double> pdd;
typedef pair<llt, llt> pll;
typedef complex<double> cd;
// const int M = 998244353;

// random_device rm;
// mt19937 rg(rm());
// default_random_engine rg(rm());
// uniform_int_distribution<int> rd(INT_MIN, INT_MAX);
// uniform_real_distribution<double> rd(0, M_PI);

void db() { cerr << "\n"; }
template <class T, class... U>
void db(T a, U... b) { cerr << a << " ", db(b...); }

inline char gc()
{
    const static int SZ = 1 << 16;
    static char buf[SZ], *p1, *p2;
    if (p1 == p2 && (p2 = buf + fread(p1 = buf, 1, SZ, stdin), p1 == p2))
        return -1;
    return *p1++;
}
void rd() {}
template <typename T, typename... U>
void rd(T &x, U &...y)
{
    x = 0;
    bool f = 0;
    char c = gc();
    while (!isdigit(c))
        f ^= !(c ^ 45), c = gc();
    while (isdigit(c))
        x = (x << 1) + (x << 3) + (c ^ 48), c = gc();
    f && (x = -x), rd(y...);
}

template <typename T>
void prt(T x)
{
    if (x < 0)
        putchar('-'), x = -x;
    if (x > 9)
        prt(x / 10);
    putchar((x % 10) ^ 48);
}

const int N = 5e5 + 5, M = 2e6 + 6;
vector<int> eg[N];
int xr[M], yr[M], wr[M], a1[M];
int in[N], ou[N], ct, ac[20][N];
int mx[N], sc[N], dp[N], ans, bs;
vector<int> q1[N], q2[N];

void dfs(int u, int fa)
{
    in[u] = ++ct;
    for (int v : eg[u])
    {
        if (v == fa)
            continue;
        ac[0][v] = u, dp[v] = dp[u] + 1;
        for (int i = 1; i < 20; i++)
            ac[i][v] = ac[i - 1][ac[i - 1][v]];
        dfs(v, u);
        tmax(sc[u], mx[v] + 1);
        if (sc[u] > mx[u])
            swap(mx[u], sc[u]);
    }
    tmax(ans, mx[u] + sc[u]), ou[u] = ct;
}

inline bool isa(int a, int p)
{
    return in[a] <= in[p] && ou[p] <= ou[a];
}

inline int lca(int u, int v)
{
    if (isa(u, v))
        return u;
    for (int i = 19; i >= 0; i--)
        if (ac[i][u] && !isa(ac[i][u], v))
            u = ac[i][u];
    return ac[0][u];
}

struct P
{
    int vp, vn, ans;
    P() { vp = vn = ans = -INF; }
    inline void ini() { vp = vn = ans = -INF; }
    P operator+(const P &rh)
    {
        P res;
        res.ans = max({ans, vp + rh.vn, rh.ans});
        res.vp = max(vp, rh.vp);
        res.vn = max(vn, rh.vn);
        return res;
    }
} tr[N << 2], vv;

void cg(int l, int r, int id, int p, int v)
{
    if (l == r)
    {
        tr[id].vp = v + p;
        tr[id].vn = v - p;
        tr[id].ans = -INF;
        return;
    }
    int m = (l + r) >> 1;
    if (p <= m)
        cg(l, m, ls(id), p, v);
    else
        cg(m + 1, r, rs(id), p, v);
    tr[id] = tr[ls(id)] + tr[rs(id)];
}

void qy(int l, int r, int id, int ql, int qr)
{
    if (ql <= l && r <= qr)
    {
        vv = vv + tr[id];
        return;
    }
    int m = (l + r) >> 1;
    if (ql <= m)
        qy(l, m, ls(id), ql, qr);
    if (qr > m)
        qy(m + 1, r, rs(id), ql, qr);
}

void slv(int u, int fa)
{
    for (int v : eg[u])
    {
        if (v == fa)
            continue;
        cg(1, ct, 1, dp[u], mx[v] + 1 == mx[u] ? sc[u] : mx[u]);
        slv(v, u);
    }
    cg(1, ct, 1, dp[u], mx[u]);
    for (int i : q1[u])
    {
        vv.ini(), qy(1, ct, 1, dp[xr[i]], dp[u]);
        tmin(ans, bs + wr[i] - (vv.ans + dp[u] - dp[xr[i]]));
        vv.ini(), qy(1, ct, 1, dp[xr[i]] + 1, dp[u]);
        int tp = vv.vn + dp[u] + dp[xr[i]];
        vv.ini(), qy(1, ct, 1, 1, dp[xr[i]]);
        tmin(ans, bs + wr[i] - (tp + vv.vn));
    }
    for (int i : q2[u])
    {
        int p = lca(xr[i], yr[i]);
        vv.ini(), qy(1, ct, 1, dp[p], dp[u]);
        // assert(dp[p] != dp[u]);
        tmin(ans, bs + wr[i] -
                      (vv.ans + dp[xr[i]] + dp[yr[i]] - (dp[p] << 1)));
        vv.ini(), qy(1, ct, 1, dp[p] + 1, dp[u]);
        if (xr[i] == u)
            a1[i] = vv.vn;
        else
            tmin(ans, bs + wr[i] - (vv.vn + a1[i] + dp[xr[i]] + dp[yr[i]]));
    }
}

signed main()
{
    int n, m;
    rd(n, m), bs = (n - 2) << 1;
    for (int i = 0; i < m; i++)
    {
        rd(xr[i], yr[i], wr[i]), xr[i]++, yr[i]++;
        if (wr[i] == 1)
            eg[xr[i]].pb(yr[i]), eg[yr[i]].pb(xr[i]);
    }
    dp[1] = 1, dfs(1, -1), ans = ((n - 1) << 1) - ans;
    for (int i = 0; i < m; i++)
    {
        assert(xr[i] != yr[i]);
        if (wr[i] == 1)
            continue;
        if (in[xr[i]] > in[yr[i]])
            swap(xr[i], yr[i]);
        if (isa(xr[i], yr[i]))
            q1[yr[i]].pb(i);
        else
            q2[xr[i]].pb(i), q2[yr[i]].pb(i);
    }
    slv(1, -1);
    if (n != 4)
        assert(ans == 8);
    prt(ans), putchar('\n');
}

• Subtask 1: 0 / 1
• Subtask 2: 0 / 2
• Subtask 3: 0 / 2
• Subtask 4: 0 / 6
• Subtask 5: 0 / 2
• Subtask 6: 0 / 3
• Subtask 7: 0 / 5
• Subtask 8: 0 / 4