ural 1057Amount of Degrees ——数位DP

link:http://acm.timus.ru/problem.aspx?space=1&num=1057

论文： 浅谈数位类统计问题  刘聪

 #include <iostream>
 #include <cstdio>
 #include <cstdlib>
 #include <cstring>
 #include <cmath>
 #include <cctype>
 #include <algorithm>
 #include <queue>
 #include <deque>
 #include <queue>
 #include <list>
 #include <map>
 #include <set>
 #include <vector>
 #include <utility>
 #include <functional>
 #include <fstream>
 #include <iomanip>
 #include <sstream>
 #include <numeric>
 #include <cassert>
 #include <ctime>
 #include <iterator>
 const int INF = 0x3f3f3f3f;
 ][] = {{-,},{,},{,-},{,},{-,-},{-,},{,-},{,}};
 using namespace std;
 ][];
 int bto2(int x, int b)
 {
     ], cnt = , ans = ;
     while (x)
     {
         tm[cnt++] = x % b; x /= b;
     }
     ; i >= ; --i)
     {
         ))
         {
             ans += ((<<(i+))-); break;
         }
         <<i);
     }
     return ans;
 }
 int calc(int x, int k)
 {
     , ans = ;
     ; i > ; --i)
     {
         <<i))
         {
             ++tot; if (tot > k) break;
             x = x ^ (<<i);
         }
         <<(i - )) <= x) ans += (a[i-][k-tot]);
     }
     if (tot + x == k) ++ans;
     return ans;
 }
 int main(void)
 {
     #ifndef ONLINE_JUDGE
     freopen("in.txt", "r", stdin );
     #endif // ONLINE_JUDGE
     int x,y,k,b;
     memset(a, , sizeof(a));
     a[][] = ;
     ; i <= ; ++i)
     {
         a[i][] = a[i-][];
         ; j <= i; ++j) a[i][j] = a[i-][j] + a[i-][j-];
     }
     while (~scanf("%d%d%d%d",&x, &y, &k, &b))
     {
         ;
         )
         {
             ans = calc(y, k) - calc(x - , k);
         }
         else
         {
             , b), Y = bto2(y, b);
             ans = calc(Y, k) - calc(X, k);
         }
         printf("%lld\n", ans);
     }
     ;
 }

走吧，小胖！