投机取巧

# include <bits/stdc++.h>
typedef unsigned long long ull;

#define getchar getchar_unlocked()
#define psbc push_back
#define v vector
#define for1 for(i = 0;i<n;i++)
#define beg(x) x.begin(),x.end()
#define mkp make_pair

using  namespace  std ;
const int MX = 1e5;
int i,j,k;
int r(){
    int x = 0,f = 1;
    char c = getchar;
    while(c<'0'||c>'9'){if(c=='-') f = -1;c = getchar;}
    while(c>='0'&&c<='9') x = (x<<1)+(x<<3)+(c^(3<<4)),c = getchar;
    return x*f;
}
bool ct[57];
int res;
int  main ( )
{
    int y1 = r(),m1 = r(),d1 = r();
    int y2 = r(),m2 = r(),d2 = r();
    for(int y = y1;y<=y2;y++){
        for(int m = m1;m<=m2;m++){
            for(int d = d1;d<=d2;d++){
                ct[y/1000%10+y/100%10+y/10%10+y/1%10+m/10%10+m/1%10+d/10%10+d/1%10] = 1;
            }
        }
    }
    for(auto i:ct){
        if(i) res++;
    }
    cout<<res;
    return  0;
}

时间复杂度: $O((y2-y1)*(m2-m1)*(d2-d1))$