11660 - Look-and-Say sequences/11660.cpp

   1 using namespace std;
   2 #include <algorithm>
   3 #include <iostream>
   4 #include <iterator>
   5 #include <numeric>
   6 #include <sstream>
   7 #include <fstream>
   8 #include <cassert>
   9 #include <climits>
  10 #include <cstdlib>
  11 #include <cstring>
  12 #include <string>
  13 #include <cstdio>
  14 #include <vector>
  15 #include <cmath>
  16 #include <queue>
  17 #include <deque>
  18 #include <stack>
  19 #include <list>
  20 #include <map>
  21 #include <set>
  22
  23 #define foreach(x, v) for (typeof (v).begin() x=(v).begin(); x !=(v).end(); ++x)
  24 #define For(i, a, b) for (int i=(a); i<(b); ++i)
  25 #define D(x) cout << #x " is " << x << endl
  26
  27 int main(){
  28     int x1, times, position;
  29     while (cin >> x1 >> times >> position) {
  30         if (x1 == 0 and times == 0 and position == 0) break;
  31         vector< int > v;
  32         while (x1 > 0) v.push_back(x1 % 10), x1 /= 10;
  33         reverse(v.begin(), v.end());
  34
  35         //printf("V is "); For(i, 0, v.size()) printf("%d ", v[i]); puts("");
  36
  37         for (int t = 0; t < times - 1; ++t) {
  38             vector< int > w;
  39
  40             for (int i = 0; i < v.size(); ) {
  41                 int j = i;
  42                 while (j < v.size() and v[i] == v[j]) j++;
  43                 int size = j - i;
  44                 //printf("%d appears %d times from [%d,%d)\n", v[i], size, i, j);
  45                 int n = w.size();
  46                 while (size > 0) w.push_back(size % 10), size /= 10;
  47                 reverse(w.begin() + n, w.end());
  48                 w.push_back(v[i]);
  49
  50                 if (w.size() > 3000) break;
  51                 i = j;
  52             }
  53
  54             v = w;
  55             //printf("V is "); For(i, 0, v.size()) printf("%d ", v[i]); puts("");
  56         }
  57         cout << v[position - 1] << endl;
  58     }
  59     return 0;
  60 }