Ural 1057 amount of degrees (Digital DP)

1057. Amount of degreestime limit: 1.0 second
Memory limit: 64 MB
Create a code to determine the amount of integers, lying in the set [ X; Y] And being a sum of exactly KDifferent integer degrees B. Example.Let X= 15, Y= 20, K= 2, B= 2. By this example 3 numbers are the sum of exactly two integer degrees of Number 2: 17 = 24 + 20,
18 = 24 + 21,
20 = 24 + 22. inputthe first line of input contains Integers XAnd Y, Separated with a space (1 ≤ X≤ Y≤0, 231? 1). The next two lines contain Integers KAnd B(1 ≤ K≤ 20; 2 ≤ B≤ 10). outputoutput shoshould contain a single integer-the amount of integers, lying XAnd Y, Being a sum of exactly KDifferent integer degrees B. Sample

Input	Output
15 2022	3

Problem Source:Rybinsk state Avia Academy
Tags:None ()
A special number is defined first. A special number is composed of k different B ^ x mails. Ask how many special numbers are in [x, y. Idea: Digital DP. DP [I] [J] indicates the binary representation. The number where I is 1 is the total number of J. Other hexadecimal formats are similar. Note the boundary. For details, see the code:

#include<algorithm>#include<iostream>#include<string.h>#include<stdio.h>#include<stdlib.h>using namespace std;const int INF=0x3f3f3f3f;const int maxn=100010;typedef long long ll;int dp[35][35],base[35],bin[35];void init(){    dp[0][0]=base[0]=1;    for(int i=1;i<=32;i++)    {        dp[i][0]=1;        base[i]=base[i-1]<<1;        for(int j=1;j<=i;j++)            dp[i][j]=dp[i-1][j]+dp[i-1][j-1];    }}int calc(int x,int k){    int i,one=0,ans=0;    for(i=31;i>=0;i--)    {        if(x&base[i])        {            if(one>k)                break;            ans+=dp[i][k-one];            one++;            x-=base[i];        }    }    if(one==k)        ans++;    return ans;}int getbin(int x,int b){    int ct=0,i,ret=0;    if(!x)        return x;    while(x)    {        bin[ct++]=x%b;        x/=b;    }    for(i=ct-1;i>=0;i--)    {        if(bin[i]>1)            break;        if(bin[i])            ret=ret<<1|1;        else            ret<<=1;    }    while(i>=0)    {        ret=ret<<1|1;        i--;    }    return ret;}int main(){    int x,y,k,b;    init();    while(~scanf("%d%d%d%d",&x,&y,&k,&b))    {        y=getbin(y,b);        x=getbin(x-1,b);        printf("%d\n",calc(y,k)-calc(x,k));    }    return 0;}

Ural 1057 amount of degrees (Digital DP)