1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57
| #include <bits/stdc++.h> using namespace std; const int N = 51; int up[N], down[N]; int arr[N]; int n; bool dfs(int depth, int i_arr, int i_up, int i_down) { if(i_up + i_down > depth) return false; if(i_arr == n+1) { return true; } int i, change = false; for(i = 1; i <= i_up; ++i) { if(up[i] < arr[i_arr]) { change = true; break; } } int temp; if(change) { temp = up[i]; up[i] = arr[i_arr]; if(dfs(depth, i_arr+1, i_up, i_down)) return true; } else if(i_up + 1 + i_down <= n){ up[i_up+1] = arr[i_arr]; if(dfs(depth, i_arr+1, i_up+1, i_down)) return true; } if(change) up[i] = temp; change = false; for(i = 1; i <= i_down; ++i) { if(down[i] > arr[i_arr]) { change = true; break; } } if(change) { temp = down[i]; down[i] = arr[i_arr]; if(dfs(depth, i_arr+1, i_up, i_down)) return true; } else if(i_up + i_down + 1 <= n){ down[i_down+1] = arr[i_arr]; if(dfs(depth, i_arr+1, i_up, i_down+1)) return true; } if(change) down[i] = temp; return false; }
int main() { while(scanf("%d", &n)) { if(n == 0) break; for(int i = 1; i <= n; ++i) scanf("%d", &arr[i]); int r = 0; while(!dfs(r,1,0,0)) r++; printf("%d\n", r); } return 0; }
|