HDU-2017 多校训练赛7-1002-Build a tree

ACM模版

描述

题解

官方题解：

其实就是 k 叉堆上的 dp……比赛时白痴了没有看这个题……浪费了。

代码

#include <cstdio>#include <algorithm>using namespace std;typedef long long ll;const int MAXN = 111;const int MAGIC = 62;const ll INF = 0x3f3f3f3f3f3f3f3f;ll n, k, X;ll F[MAXN];ll C[MAXN];ll HR(ll a, ll n, ll k){    if (a + 1 <= n / k && (a + 1) * k < n)    {        return HR((a + 1) * k, n, k) + 1;    }    return 0;}ll HL(ll a, ll n, ll k){    if (a <= (n - 1) / k && a * k + 1 < n)    {        return HL(a * k + 1, n, k) + 1;    }    X = a;    return 0;}ll slove(ll L, ll R, ll n, ll k){    ll hr = HR(R, n, k);    ll hl = HL(L, n, k);    if (L == R)    {        if (hr == hl)        {            return F[hr];        }        if (L + 1 <= n / k && (L + 1) * k < n)        {            return (C[hr] + n - X) ^ slove(L * k + 1, (L + 1) * k, n, k);        }        return (C[hr] + n - X) ^ slove(L * k + 1, n - 1, n, k);    }    if (hr == hl)    {        if ((R - L + 1) & 1)        {            return F[hr];        }        return 0;    }    ll mid = (L + R) >> 1;    return slove(L, mid, n, k) ^ slove(mid + 1, R, n, k);}ll cal(ll n, ll m){    if (m == 1)    {        return 0;    }    if (n >= m)    {        if ((n - m + 1) & 1)        {            return m + cal(n - m, m >> 1);        }        return cal(n - m, m >> 1);    }    return cal(n, m >> 1);}int main(){    int T;    scanf("%d", &T);    while (T--)    {        scanf("%lld%lld", &n, &k);        if (k == 1)        {            printf("%lld\n", cal(n, 1ll << MAGIC) + (((n + 1) / 2) & 1));            continue;        }        F[0] = 1;        C[0] = 1;        for (ll i = 1, s = INF - 1, j = 1; ; j++)        {            if (s / k < i)            {                break;            }            i *= k;            s -= i;            if (k & 1)            {                F[j] = F[j - 1];            }            F[j] ^= INF - s;            C[j] = C[j - 1] + i;        }        printf("%lld\n", slove(0, 0, n, k));    }    return 0;}