[THOJ 2471] lis 最值字典序

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <cstdlib>
 4 #include <cctype>
 5 #include <algorithm>
 6 using namespace std;
 7 #define F(i, a, b) for (register int i = (a); i <= (b); i++)
 8 #define D(i, a, b) for (register int i = (a); i >= (b); i--)
 9 inline int rd(void) {
10     int f = 1; char c = getchar(); for (; !isdigit(c); c = getchar()) if (c == ‘-‘) f = -1;
11     int x = 0; for (; isdigit(c); c = getchar()) x = x*10+c-‘0‘; return x*f;
12 }
13 
14 const int N = 100005;
15 
16 int n, L;
17 struct Data {
18     int key, pos;
19     friend inline bool operator < (Data A, Data B) { return A.key != B.key ? A.key < B.key : A.pos < B.pos; }
20 }w[N];
21 int f[N], tr[N];
22 
23 inline int lowbit(int i) { return i & -i; }
24 inline void Add(int x, int w) { for (int i = x; i <= n; i += lowbit(i)) tr[i] = max(tr[i], w); }
25 inline int Query(int x) { int Max = 0; for (int i = x; i > 0; i -= lowbit(i)) Max = max(Max, tr[i]); return Max; }
26 
27 int main(void) {
28     #ifndef ONLINE_JUDGE
29         freopen("lis.in", "r", stdin);
30     #endif
31     
32     n = rd(), L = rd();
33     F(i, 1, n) w[i] = (Data){rd(), i};
34     sort(w+1, w+n+1);
35     
36     D(i, n, 1) {
37         f[i] = Query(n - w[i].pos + 1) + 1;
38         Add(n - w[i].pos + 1, f[i]);
39     }
40     
41     if (*max_element(f+1, f+n+1) < L) puts("impossible"), 0;
42     for (int Last = -1, W = -1, i = 1; i <= n && L >= 1; i++)
43         if (f[i] >= L && Last < w[i].pos && W < w[i].key)
44             printf("%d ", w[i].key), L--, Last = w[i].pos, W = w[i].key;
45     puts("");
46     
47     return 0;
48 }