HDU2089[不要62]--数位DP

来源：互联网发布：java软件是什么编辑：程序博客网时间：2024/06/05 16:55

【链接】
hdu2089

【解题报告】
简单的数位DP

#include<cstdio>#include<cstring>#include<algorithm>using namespace std;const int maxn=25;int n,m,ans,len,f[maxn][10],a[maxn];inline int Read(){    int res=0; char ch=getchar();    while (ch<'0'||ch>'9') ch=getchar();    while (ch>='0'&&ch<='9') res=res*10+ch-48,ch=getchar();    return res;}int Dfs(int x,int las,bool pd){    if (x>len) return 1;    if (!pd&&f[x][las]) return f[x][las];    int MAX=9; if (pd) MAX=a[x]; f[x][las]=0;    for (int i=0; i<=MAX; i++)     if ((las!=6&&i!=4)||(las==6&&i!=2&&i!=4)) f[x][las]+=Dfs(x+1,i,pd&(i==a[x]));    return f[x][las];}void Work(){    memset(f,0,sizeof(f));    a[0]=len=0;int x=n-1;    while (x) a[++len]=x%10,x/=10;    for (int i=1; i<=len/2; i++) swap(a[i],a[len-i+1]);    ans=Dfs(1,0,1);    memset(f,0,sizeof(f));    a[0]=len=0; x=m;    while (x) a[++len]=x%10,x/=10;    for (int i=1; i<=len/2; i++) swap(a[i],a[len-i+1]);    printf("%d\n",Dfs(1,0,1)-ans);    n=Read(); m=Read();}int main(){    freopen("2089.in","r",stdin);    freopen("2089.out","w",stdout);    n=Read(); m=Read();    while (n||m) Work();    return 0;}

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