hdu2089 不要62
1 1000 0
80
第一次做数位dp。
所以就挑一道最简单的来做。
dp[i][j]代表只有i位且第i位为j的符合个数:
#include<stdio.h>#include<string.h>int dp[10][12];int n,m;int a[10];int tran(int nn,int aa[]){int po = 0;while(nn){aa[po++] = nn%10;nn = nn/10;}return po-1;}int DFS(int len,int ss,int flag,int doing,int ab) //ab代表上一位是否等于6{if(len<0)return flag;if(!doing && dp[len+1][ss]!=-1)return dp[len+1][ss];int end = doing?a[len]:9;int ans = 0;for(int i=0;i<=end;i++){if(i!=4 && (i!=2 || !ab))ans+=DFS(len-1,i,flag,doing&&end==i,i==6);}if(!doing)dp[len+1][ss] = ans;return ans;}int main(){memset(dp,-1,sizeof(dp));while(scanf("%d%d",&n,&m) && n+m!=0){int alen,mm=0;alen = tran(n-1,a);mm+=DFS(alen,0,1,1,0);alen = tran(m,a);mm=DFS(alen,0,1,1,0)-mm; printf("%d\n",mm);}return 0;}