HDU 3555 Bomb

模板题

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
ll num;
int a[20],len;
ll dp[2][20],ten[20];
ll dfs(int pos,bool pre,bool lim)
{
    int Max=lim?a[pos]:9;
    if(pos==1)return Max==9&&pre;
    if(!lim&&dp[pre][pos]!=-1)return dp[pre][pos];
    ll ret=0;
    for(int i=0;i<=Max;++i)
    {
        //printf("%d:%d ",pos,i);
        if(i==9&&pre)ret+=lim?(num%ten[pos-1]+1):ten[pos-1];
        else ret+=dfs(pos-1,i==4,lim&&i==Max);
        //printf("%d
",ret);
    }
    if(!lim)dp[pre][pos]=ret;
    return ret;
}
ll solve(ll x)
{
    len=0;
    while(x)
    {
        a[++len]=x%10;
        x/=10;
    }
    return dfs(len,0,1);//todo
}
int main()
{
    //freopen("Input.txt","r",stdin);
    ten[0]=1;
    for(int i=1;i<=19;++i)ten[i]=ten[i-1]*10;
    memset(dp,-1,sizeof dp);
    int t;scanf("%d",&t);
    while(t--)
    {
        scanf("%I64d",&num);
        printf("%I64d
",solve(num));
    }
}