hdu 3555 Bomb（数位DP）

Problem Description

The counter-terrorists found a time bomb in the dust. But this time the terrorists improve on the time bomb. The number sequence of the time bomb counts from 1 to N. If the current number sequence includes the sub-sequence "49", the power of the blast would add one point.
Now the counter-terrorist knows the number N. They want to know the final points of the power. Can you help them?

 

Input

The first line of input consists of an integer T (1 <= T <= 10000), indicating the number of test cases. For each test case, there will be an integer N (1 <= N <= 2^63-1) as the description.

The input terminates by end of file marker.

 

Output

For each test case, output an integer indicating the final points of the power.

 

Sample Input

3150500

 

Sample Output

0115
Hint
From 1 to 500, the numbers that include the sub-sequence "49" are "49","149","249","349","449","490","491","492","493","494","495","496","497","498","499",so the answer is 15.
 

 

题意：与HDU2089一样的意思，要求1~n的范围内含有49的数字的个数；

思路：dfs+记忆化，注意输入输出为64位整型；

代码：

#include<cstdio>#include<algorithm>#include<cstring>using namespace std;__int64 dp[500][2],a[500];__int64 dfs(int len,int p,int d){    if(!len)       return 1;    if(dp[len][p]&&!d)       return dp[len][p];    int f=a[len];    __int64 ans=0;    int s=d?f:9;    for(int i=0;i<=s;i++)    {        if(p&&i==9)            continue;        ans=ans+dfs(len-1,i==4,d&&i==s);    }    if(!d)       dp[len][p]=ans;    return ans;}__int64 solve(__int64 n){    int len=0;    while(n)    {        a[++len]=n%10;        n=n/10;    }    return dfs(len,0,1);}int main(){    int t;    scanf("%d",&t);    memset(dp,0,sizeof(dp));    __int64 n,ans;    while(t--)    {        scanf("%I64d",&n);        ans=solve(n);        printf("%I64d\n",n-ans+1);    }}