dfs打表 C. Classy Numbers
C. Classy Numbers
C. Classy Numbers time limit per test 3 seconds memory limit per test 256 megabytes input standard input output standard outputLet‘s call some positive integer classy if its decimal representation contains no more than 33 non-zero digits. For example, numbers 44, 200000200000, 1020310203 are classy and numbers
You are given a segment [L;R][L;R]. Count the number of classy integers xx such that L≤x≤RL≤x≤R.
Each testcase contains several segments, for each of them you are required to solve the problem separately.
InputThe first line contains a single integer TT (
Each of the next TT lines contains two integers LiLi and RiRi (1≤Li≤Ri≤10181≤Li≤Ri≤1018).
OutputPrint TT lines — the ii-th line should contain the number of classy integers on a segment [Li;Ri][Li;Ri].
Example input Copy4
1 1000
1024 1024
65536 65536
999999 1000001
1000
1
0
2
題意：找出區間[L, R]之間最多有三位是非零數字的十進制數的個數；
思路：用構造出所有的滿足題意的數，然後排序，二分找；
也可數位DP
/***********************************************/
ll a,b,n;
vector<ll>V;
void dfs(ll x,int oo,int len)
{
V.push_back(x);
if(len==18) return ;
dfs(x*10,oo,len+1);
if(oo<3)
for(int i=1;i<=9;i++) dfs(x*10+i,oo+1,len+1);
}
int main()
{
for(ll i=1;i<=9;i++) {
dfs(i,1,1);
}
V.push_back(1e18);
sort(V.begin(),V.end());
scl(n);
while(n--)
{
ll ans=0;
scl2(a,b);
ll l=lower_bound(V.begin(),V.end(),a)-V.begin();
ll r=upper_bound(V.begin(),V.end(),b)-V.begin();
cout<<r-l<<endl;
}
return 0;
}
dfs打表 C. Classy Numbers