牛客练习赛13B 幸运数字2

题目链接：https://ac.nowcoder.com/acm/contest/70/B

题目大意：

　　略

分析：

　　先DFS求出所有幸运数，然后暴力即可

代码如下：

  1 #pragma GCC optimize("Ofast")
  2 #include <bits/stdc++.h>
  3 using namespace std;
  4 
  5 #define INIT() std::ios::sync_with_stdio(false);std::cin.tie(0);
  6 #define Rep(i,n) for (int i = 0; i < (n); ++i)
  7 #define For(i,s,t) for (int i = (s); i <= (t); ++i)
  8 #define rFor(i,t,s) for (int i = (t); i >= (s); --i)
  9 #define ForLL(i, s, t) for (LL i = LL(s); i <= LL(t); ++i)
 10 #define rForLL(i, t, s) for (LL i = LL(t); i >= LL(s); --i)
 11 #define foreach(i,c) for (__typeof(c.begin()) i = c.begin(); i != c.end(); ++i)
 12 #define rforeach(i,c) for (__typeof(c.rbegin()) i = c.rbegin(); i != c.rend(); ++i)
 13 
 14 #define pr(x) cout << #x << " = " << x << "  "
 15 #define prln(x) cout << #x << " = " << x << endl
 16 
 17 #define LOWBIT(x) ((x)&(-x))
 18 
 19 #define ALL(x) x.begin(),x.end()
 20 #define INS(x) inserter(x,x.begin())
 21 
 22 #define ms0(a) memset(a,0,sizeof(a))
 23 #define msI(a) memset(a,inf,sizeof(a))
 24 #define msM(a) memset(a,-1,sizeof(a))
 25 
 26 #define pii pair<int,int> 
 27 #define piii pair<pair<int,int>,int> 
 28 #define MP make_pair
 29 #define PB push_back
 30 #define ft first
 31 #define sd second
 32 
 33 template<typename T1, typename T2>
 34 istream &operator>>(istream &in, pair<T1, T2> &p) {
 35     in >> p.first >> p.second;
 36     return in;
 37 }
 38 
 39 template<typename T>
 40 istream &operator>>(istream &in, vector<T> &v) {
 41     for (auto &x: v)
 42         in >> x;
 43     return in;
 44 }
 45 
 46 template<typename T1, typename T2>
 47 ostream &operator<<(ostream &out, const std::pair<T1, T2> &p) {
 48     out << "[" << p.first << ", " << p.second << "]" << "\n";
 49     return out;
 50 }
 51 
 52 typedef long long LL;
 53 typedef unsigned long long uLL;
 54 typedef pair< double, double > PDD;
 55 typedef set< int > SI;
 56 typedef vector< int > VI;
 57 const double EPS = 1e-10;
 58 const int inf = 1e9 + 9;
 59 const LL mod = 1e9 + 7;
 60 const int maxN = 1e5 + 7;
 61 const LL ONE = 1;
 62 
 63 LL l, r, ans;
 64 LL lucky[1500], n; 
 65 
 66 // 求所有幸运数 
 67 inline void dfs(LL x, int cnt) {
 68     if(cnt > 9) return;
 69     lucky[n++] = x;
 70     dfs(x*10 + 4, cnt + 1);
 71     dfs(x*10 + 7, cnt + 1);
 72 }
 73 
 74 int main(){
 75     INIT(); 
 76     cin >> l >> r;
 77     lucky[n++] = 4444444444;
 78     dfs(0, 0);
 79     sort(lucky, lucky + n);
 80     
 81     int j = lower_bound(lucky, lucky + n, l) - lucky;
 82     
 83     while(l <= r) {
 84         ans += (min(lucky[j], r) - l + 1) * lucky[j];
 85         l = lucky[j++] + 1;
 86     }
 87     
 88     cout << ans << endl;
 89     return 0;
 90 }
 91 
 92 /*
 93 1 1000000000
 94 1394672350065645019
 95 
 96 1 1000
 97 1397683
 98 
 99 447 447477474
100 168389348342066109
101 
102 1 436278568
103 163403864955643707
104 
105 1 4328955
106 16190029435407
107 
108 4328956 4444444
109 513284393116
110 
111 4328956 436278568
112 163387674926208300
113 
114 2354 543262
115 231508617956
116 
117 999999999 1000000000
118 8888888888
119 */

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