Codeforces 833 C - Ever-Hungry Krakozyabra

时间:2023-12-20 23:32:44

思路:

首先,inedible tails 的个数最多为C(18+9,9)个(用隔板法),所以我们暴力出所有的 inedible tails,然后检查一下在[L, R]这段区间是否存在这个inedible tails

检查的时候用了和数位dp差不多的方法,设一个下界和上界,只要之前的既没有达到上界也没有达到下界,后面就可以随便填了,说明存在

#pragma GCC optimize(2)
#pragma GCC optimize(3)
#pragma GCC optimize(4)
#include<bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define pi acos(-1.0)
#define LL long long
//#define mp make_pair
#define pb push_back
#define ls rt<<1, l, m
#define rs rt<<1|1, m+1, r
#define ULL unsigned LL
#define pll pair<LL, LL>
#define pii pair<int, int>
#define piii pair<pii, int>
#define mem(a, b) memset(a, b, sizeof(a))
#define fio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define fopen freopen("in.txt", "r", stdin);freopen("out.txt", "w", stout);
//head int l[], r[], f[], ans = , cnt = ;
bool check(int pos, bool Llimit, bool Rlimit) {
if(!Llimit && !Rlimit) return true;
if(pos == ) return true;
int down = Llimit ? l[pos] : ;
int up = Rlimit ? r[pos] : ;
for (int i = down; i <= up; i++) {
if(f[i]) {
f[i]--;
bool flag = check(pos-, Llimit&&i==l[pos], Rlimit&&i==r[pos]);
f[i]++;
if(flag) return true; }
}
return false;
}
void dfs(int pos, int res) {
if(pos == ) {
f[pos] = res;
if(check(cnt, , )) ans++;
return ;
}
for (int i = ; i <= res; i++) {
f[pos] = i;
dfs(pos+, res - i);
}
}
int solve(LL L, LL R) {
cnt = ;
while(L) {
l[++cnt] = L%;
L /= ;
} cnt = ;
while(R) {
r[++cnt] = R%;
R /= ;
}
ans = ;
dfs(, cnt);
return ans;
}
int main() {
LL L, R;
scanf("%lld %lld", &L, &R);
printf("%d\n", solve(L, R));
return ;
}