HDU 4734 F(x) (2013成都网络赛,数位DP)

F(x)

Time Limit: 1000/500 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 382    Accepted Submission(s): 137

Problem Description
For a decimal number x with n digits (AnAn-1An-2 ... A2A1), we define its weight as F(x) = An * 2n-1 + An-1 * 2n-2 + ... + A2 * 2 + A1 * 1. Now you are given two numbers A and B, please calculate how many numbers are there between 0 and B, inclusive, whose weight is no more than F(A).
 
Input
The first line has a number T (T <= 10000) , indicating the number of test cases.
For each test case, there are two numbers A and B (0 <= A,B < 109)
 
Output
For every case,you should output "Case #t: " at first, without quotes. The t is the case number starting from 1. Then output the answer.
 
Sample Input
3
0 100
1 10
5 100
 
Sample Output
Case #1: 1
Case #2: 2
Case #3: 13
 
Source
 
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liuyiding
 

数位DP的水题

dp[i][j]表示i位值<=j 的总数

/* ***********************************************
Author :kuangbin
Created Time :2013/9/14 星期六 12:45:42
File Name :2013成都网络赛\1007.cpp
************************************************ */ #pragma comment(linker, "/STACK:1024000000,1024000000")
#include <stdio.h>
#include <string.h>
#include <iostream>
#include <algorithm>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <string>
#include <math.h>
#include <stdlib.h>
#include <time.h>
using namespace std; int dp[][]; int bit[]; int dfs(int pos,int num,bool flag)
{
if(pos == -)return num >= ;
if(num < )return ;
if(!flag && dp[pos][num] != -)
return dp[pos][num];
int ans = ;
int end = flag?bit[pos]:;
for(int i = ;i <= end;i++)
{ ans += dfs(pos-,num - i*(<<pos),flag && i==end);
}
if(!flag)dp[pos][num] = ans;
return ans;
} int F(int x)
{
int ret = ;
int len = ;
while(x)
{
ret += (x%)*(<<len);
len++;
x /= ;
}
return ret;
}
int A,B;
int calc()
{
int len = ;
while(B)
{
bit[len++] = B%;
B/=;
//cout<<bit[len-1]<<endl;
}
//cout<<F(A)<<endl;
return dfs(len-,F(A),);
} int main()
{
//freopen("in.txt","r",stdin);
//freopen("out.txt","w",stdout);
int T;
int iCase = ;
scanf("%d",&T);
memset(dp,-,sizeof(dp));
while(T--)
{
iCase++;
scanf("%d%d",&A,&B);
printf("Case #%d: %d\n",iCase,calc());
}
return ;
}
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