[暑假集训--数位dp]hdu5787 K-wolf Number

Alice thinks an integer x is a K-wolf number, if every K adjacent digits in decimal representation of x is pairwised different.
Given (L,R,K), please count how many K-wolf numbers in range of L,RL,R .

Input

The input contains multiple test cases. There are about 10 test cases.

Each test case contains three integers L, R and K.

1≤L≤R≤1e18
2≤K≤52≤K≤5

Output

For each test case output a line contains an integer.

Sample Input

1 1 2
20 100 5

Sample Output

1
72

问有多少个数，任意连续k位都不相同

记一下前k-1位，有没有前导零

#include<cstdio>
#include<iostream>
#include<cstring>
#include<cstdlib>
#include<algorithm>
#include<cmath>
#include<queue>
#include<deque>
#include<set>
#include<map>
#include<ctime>
#define LL long long
#define inf 0x7ffffff
#define pa pair<int,int>
#define mkp(a,b) make_pair(a,b)
#define pi 3.1415926535897932384626433832795028841971
using namespace std;
inline LL read()
{
    LL x=0,f=1;char ch=getchar();
    while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
    while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
    return x*f;
}
LL n,len,l,r,k;
LL f[20][2300][2];
int zhan[110];
int d[110];
inline LL dfs(int now,int stat,int lead,int fp)
{
    if (now==1)return 1;
    if (!fp&&f[now][stat][lead]!=-1)return f[now][stat][lead];
    LL ans=0,mx=fp?d[now-1]:9;
    int lst=0;
    for(int i=now;i<=min(now+k-2,len);i++)if (zhan[i]!=-1)lst|=1<<zhan[i];
    for (int i=0;i<=mx;i++)
    {
        if (lst&(1<<i))continue;
        if (i==0&&lead&&now-1!=1)zhan[now-1]=-1;else zhan[now-1]=i;
        if (zhan[now-1]!=-1)lst|=(1<<i);
        ans+=dfs(now-1,lst,lead&&i==0&&now-1!=1,fp&&(i==d[now-1]));
        if (zhan[now-1]!=-1)lst-=(1<<i);
    }
    if (!fp)f[now][stat][lead]=ans;
    return ans;
}
inline LL calc(LL x)
{
    if (!x)return 1;
    LL xxx=x;
    len=0;
    while (xxx)
    {
        d[++len]=xxx%10;
        xxx/=10;
    }
    LL sum=0;
    for (int i=0;i<=d[len];i++)
    {
        if (i==0&&len!=1)zhan[len]=-1;else zhan[len]=i;
        if (zhan[len]!=-1)sum+=dfs(len,1<<zhan[len],zhan[len]==-1,i==d[len]);
        else sum+=dfs(len,0,zhan[len]==-1,i==d[len]);
        zhan[len]=-1;
    }
    return sum;
}
main()
{
    while (~scanf("%lld%lld%lld",&l,&r,&k))
    {
        memset(f,-1,sizeof(f));
        printf("%lld
",calc(r)-calc(l-1));
    }
}