范围较小，模拟即可（数位dp还不会）😭

from math import sqrt,ceil,gcd,log;re=lambda:map(int,input().split())
a = []
res = 0
for i in range(0, 10001):
    res += str(i).count('7')
    a.append(res)
t, = re()
for _ in range(t):
    n, = re()
    print(a[n])

#include <stdio.h>

int main()

{

int t;

scanf("%d",&t);

while(t--){

int n;

scanf("%d",&n);

int sum=0;

for(int i=0;i<=n;i++){

int a=i;

while(a!=0){

if(a%10==7){

sum++;

}

a/=10;

}

}

printf("%d\n",sum);

}

return 0;

}

int count (int n)
{
int count1=0;
for(int i=0;i<=n;i++)
{
int temp=i;
while(temp>0)

{
if(temp%10==7)
{
count1++;
}
temp/=10;
}
}
return count1;
}
int main()
{
int n,m;
scanf("%d",&m);
while(m--)
{
scanf("%d",&n);
int result=count(n);
printf("%d\n",result);
}
return 0;
}