給m，n，問含有m個0的第k個數，是幾位數，最高位是多少

#include <iostream>
#include <algorithm>
#include <cstring>
#include <cstdio>
#include <string>
#include <cmath>
using namespace std;
#define inf 0x3f3f3f3f
#define PI acos(-1.0)

typedef __int64 ll;
const int maxn=30;
ll dp[maxn][maxn][maxn],k,m,a[30];

ll dfs(int pos,int num,bool limit,bool lead)
{
    if(pos==-1)
    {
        if(lead)
            return 0;
        return num==m;
    }
    if(!limit&&!lead&&dp[pos][num][m]!=-1)
        return dp[pos][num][m];
    int up=limit?a[pos]:9;
    ll ans=0;
    for(int i=0;i<=up;i++)
    {
        if(lead)
            ans+=dfs(pos-1,num,limit&&a[pos]==i,lead&&i==0);
        else
        {
            if(i==0)
                ans+=dfs(pos-1,num+1,limit&&a[pos]==i,lead&&i==0);
            else
                ans+=dfs(pos-1,num,limit&&a[pos]==i,lead&&i==0);
        }
    }
    if(!limit&&!lead)
        dp[pos][num][m]=ans;
    return ans;
}

ll solve(ll x)
{
    if(x<0)
        return 0;
    int pos=0;
    while(x)
    {
        a[pos++]=x%10;
        x/=10;
    }
    return dfs(pos-1,0,true,true);
}

int main()
{
    int t;
    scanf("%d",&t);
    memset(dp,-1,sizeof(dp));
    ll ans=0;
    while(t--)
    {
   //     cin >> m >> k;
        scanf("%I64d%I64d",&m,&k);
        ll l=1,r=9e18,mid;
        while(l<r-1)
        {
            mid=(r+l)/2;
            if(solve(mid)>=k)
                r=mid;
            else
                l=mid;
        }
        ll len=(ll)log10(r*1.0)+1;
        l=len-1;
        ll s=1;
        while(l--)
            s*=10;
        printf("%I64d %I64d\n",len,r/s);
    }
    return 0;
}