数学 Codeforces Round #219 (Div. 2) B. Making Sequences is Fun

 

题目传送门

 1 /*  2  数学：这题一直WA在13组上，看了数据才知道是计算cost时超long long了  3  另外不足一个区间的直接计算个数就可以了  4 */  5 #include <cstdio>  6 #include <cmath>  7 #include <iostream>  8 #include <algorithm>  9 #include <cstring> 10 using namespace std; 11 12 typedef unsigned long long ull; 13 int get_len(ull x) 14 { 15 int ret = 0; 16 while (x) { 17 x /= 10; ret++; 18  } 19 return ret; 20 } 21 22 23 int main(void) //Codeforces Round #219 (Div. 2) B. Making Sequences is Fun 24 { 25 //freopen ("B.in", "r", stdin); 26 27  ull w, m, k; 28 while (cin >> w >> m >> k) { 29 int len = get_len (m); ull mx = 0; 30 for (int i=1; i<=len; ++i) { 31 mx = mx * 10 + 9; 32  } 33 34 ull ans = 0; ull cost = (mx - m + 1) * k * len; 35 while (cost <= w) { 36 w -= cost; ans += (mx - m + 1); 37 len++; m = mx + 1; mx = mx * 10 + 9; 38 cost = (mx - m + 1) * k * len; 39  } 40 41 ans += w / (len * k); 42 cout << ans << endl; 43  } 44 45 return 0; 46 }

 1 #include <cstdio>

 2 #include <cmath>

 3 #include <iostream>

 4 #include <algorithm>

 5 #include <cstring>

 6 using namespace std;  7 

 8 typedef long long ll;  9 int get_len(ll x) 10 { 11     int ret = 0; 12     while (x) { 13         x /= 10;    ret++; 14  } 15     return ret; 16 } 17 

18 

19 int main(void)      //Codeforces Round #219 (Div. 2) B. Making Sequences is Fun

20 { 21     //freopen ("B.in", "r", stdin);

22 

23  ll w, m, k; 24     while (scanf ("%I64d%I64d%I64d", &w, &m, &k) == 3) { 25         int len = get_len (m);   ll mx = 0; 26         for (int i=1; i<=len; ++i) { 27             mx = mx * 10 + 9; 28  } 29 

30         ll ans = 0, now = 0, tot = 0; 31         while (true) { 32             now = mx - m + 1;   tot = w / (k * len); 33             if (now < tot) { 34                 ans += now; w -= now * k * len; 35                 m = mx + 1; mx = mx * 10 + 9;   len++; 36  } 37             else { 38                 ans += tot; break; 39  } 40  } 41         

42         printf ("%I64d\n", ans); 43  } 44 

45     return 0; 46 }

按个数比较