牛客练习赛43B Tachibana Kanade Loves Probability

题目链接：https://ac.nowcoder.com/acm/contest/548/C
题目大意

　　略
分析

　　利用快速幂先移到 k1 位，然后开始一个一个取余数。
代码如下

  1 #include <bits/stdc++.h>
  2 using namespace std;
  3  
  4 #define INIT() std::ios::sync_with_stdio(false);std::cin.tie(0);
  5 #define Rep(i,n) for (int i = 0; i < (n); ++i)
  6 #define For(i,s,t) for (int i = (s); i <= (t); ++i)
  7 #define rFor(i,t,s) for (int i = (t); i >= (s); --i)
  8 #define ForLL(i, s, t) for (LL i = LL(s); i <= LL(t); ++i)
  9 #define rForLL(i, t, s) for (LL i = LL(t); i >= LL(s); --i)
 10 #define foreach(i,c) for (__typeof(c.begin()) i = c.begin(); i != c.end(); ++i)
 11 #define rforeach(i,c) for (__typeof(c.rbegin()) i = c.rbegin(); i != c.rend(); ++i)
 12  
 13 #define pr(x) cout << #x << " = " << x << "  "
 14 #define prln(x) cout << #x << " = " << x << endl
 15  
 16 #define LOWBIT(x) ((x)&(-x))
 17  
 18 #define ALL(x) x.begin(),x.end()
 19 #define INS(x) inserter(x,x.begin())
 20  
 21 #define ms0(a) memset(a,0,sizeof(a))
 22 #define msI(a) memset(a,inf,sizeof(a))
 23 #define msM(a) memset(a,-1,sizeof(a))
 24 #define mcy(d,s) memcpy(d, s, sizeof(s))
 25 
 26 #define MP make_pair
 27 #define PB push_back
 28 #define ft first
 29 #define sd second
 30  
 31 template<typename T1, typename T2>
 32 istream &operator>>(istream &in, pair<T1, T2> &p) {
 33     in >> p.first >> p.second;
 34     return in;
 35 }
 36  
 37 template<typename T>
 38 istream &operator>>(istream &in, vector<T> &v) {
 39     for (auto &x: v)
 40         in >> x;
 41     return in;
 42 }
 43  
 44 template<typename T1, typename T2>
 45 ostream &operator<<(ostream &out, const std::pair<T1, T2> &p) {
 46     out << "[" << p.first << ", " << p.second << "]" << "
";
 47     return out;
 48 }
 49 
 50 inline int gc(){
 51     static const int BUF = 1e7;
 52     static char buf[BUF], *bg = buf + BUF, *ed = bg;
 53     
 54     if(bg == ed) fread(bg = buf, 1, BUF, stdin);
 55     return *bg++;
 56 } 
 57 
 58 inline int ri(){
 59     int x = 0, f = 1, c = gc();
 60     for(; c<48||c>57; f = c=='-'?-1:f, c=gc());
 61     for(; c>47&&c<58; x = x*10 + c - 48, c=gc());
 62     return x*f;
 63 }
 64  
 65 typedef long long LL;
 66 typedef unsigned long long uLL;
 67 typedef pair< double, double > PDD;
 68 typedef pair< int, int > PII;
 69 typedef pair< string, int > PSI;
 70 typedef set< int > SI;
 71 typedef vector< int > VI;
 72 typedef map< int, int > MII;
 73 typedef pair< LL, LL > PLL;
 74 typedef vector< LL > VL;
 75 typedef vector< VL > VVL;
 76 const double EPS = 1e-10;
 77 const LL inf = 0x7fffffff;
 78 const LL infLL = 0x7fffffffffffffffLL;
 79 const LL mod = 1e9 + 7;
 80 const int maxN = 5e3 + 7;
 81 const LL ONE = 1;
 82 const LL evenBits = 0xaaaaaaaaaaaaaaaa;
 83 const LL oddBits = 0x5555555555555555;
 84 
 85 LL T, m, n, k1, k2;
 86 
 87 // Calculate x^y % p
 88 inline LL pow_mod(LL x, LL y, LL p = mod){
 89     LL ret = 1;
 90     while(y){
 91         if(y & 1) ret = (ret * x) % p;
 92         x = (x * x) % p;
 93         y >>= 1;
 94     }
 95     return ret;
 96 } 
 97 
 98 int main(){
 99     INIT(); 
100     cin >> T;
101     while(T--){
102         cin >> m >> n >> k1 >> k2;
103         m = m * pow_mod(10, k1-1, n) % n;
104         
105         Rep(i, k2-k1+1) {
106             m *= 10;
107             cout << m / n;
108             m %= n;
109         }
110         cout << endl;
111     }
112     return 0;
113 }
View Code