4521: [Cqoi2016]手機號碼
阿新 • • 發佈:2019-01-05
比較基本的數位DP,限制都較為簡單;
#include<bits/stdc++.h>
#define rep(i,k,n) for(int i=k;i<=n;i++)
#define rep2(i,k,n) for(int i=k;i>=n;i--)
using namespace std;
typedef long long ll;
const int N=13;
void upd(ll& x,ll y){x+=y;}
ll f[N][N][3][3][2][2],L,R,a[N],top;
//f[位][首位][連續][4,8][是否已經有連續的三個][上界0,1]
ll solve(ll x){
memset(f,0,sizeof(f));
top=0;for(;x;a[++top]=x%10,x/=10);
rep(i,0,9)f[0][i][0][0][0][0]=f[0][i][0][0][0][1]=1;
rep(i,0,top-1){
rep(now,0,9){
rep(ne,0,9){
int op=(ne==now);
int ss=(ne==4)|((ne==8)<<1);
rep(len,0,2 ){
if(!len && !op)continue;
int ok=((len==2) && op);
if(len==2 && !op)op=-1;
rep(s,0,2){
if((ss|s)==3)continue;
rep(_3,0,1){
ll res0=f[i][now][len][s][_3][0 ];
ll res1=f[i][now][len][s][_3][1];
ll& goal0=f[i+1][ne][min(2,len+op)][ss|s][_3|ok][0];
ll& goal1=f[i+1][ne][min(2,len+op)][ss|s][_3|ok][1];
upd(goal0,res0);
if(ne<a[i+1])upd(goal1,res0);
else if(ne==a[i+1])upd(goal1,res1);
}
}
}
}
}
}
ll ans=0;
rep(i,0,9)rep(len,0,2)rep(s,0,2)upd(ans,f[top][i][len][s][1][1]);
return ans;
}
int main(){
scanf("%lld%lld",&L,&R);
ll lim=10000000000;
ll res1=solve(R);
ll res2=solve(max(lim,L-1));
printf("%lld\n",res1-res2+(L==lim));
}