BZOJ2096 [Poi2010]Pilots

 1 /**************************************************************
 2     Problem: 2096
 3     User: rausen
 4     Language: C++
 5     Result: Wrong_Answer
 6 ****************************************************************/
 7  
 8 #include <cstdio>
 9 #include <algorithm>
10  
11 using namespace std;
12 const int N = 3000005;
13 const int Maxlen = 12 * N + 105;
14  
15 int n, k, ans = 1;
16 int a[N], q[2][N], l[2], r[2];
17 char buf[Maxlen], *c = buf;
18 int Len;
19  
20 inline int read() {
21     int x = 0, sgn = 1;
22     while (*c < ‘0‘ || ‘9‘ < *c) {
23             if (*c == ‘-‘) sgn = -1; 
24             ++c;
25         }
26     while (‘0‘ <= *c && *c <= ‘9‘)
27         x = x * 10 + *c - ‘0‘, ++c;
28     return sgn * x;
29 }
30  
31 inline void pop_tail_max(int i) {
32     while (l[0] <= r[0] && a[q[0][r[0]]] <= a[i])
33         --r[0];
34     q[0][++r[0]] = i;
35 }
36  
37 inline void pop_tail_min(int i) {
38     while (l[1] <= r[1] && a[q[1][r[1]]] >= a[i])
39         --r[1];
40     q[1][++r[1]] = i;
41 }
42  
43 int main() {
44     int i, tmp;
45     Len = fread(c, 1, Maxlen, stdin);
46     buf[Len] = ‘\0‘;
47     k = read(), n = read();
48     for (i = 1; i <= n; ++i)
49         a[i] = read();
50     l[0] = l[1] = 1;
51     for (i = 1; i <= n; ++i) {
52         pop_tail_min(i);
53         pop_tail_max(i);
54         while (a[q[0][l[0]]] - a[q[1][l[1]]] > k)
55             if (q[0][l[0]] < q[1][l[1]]) tmp = q[0][l[0]++] + 1;
56             else tmp = q[1][l[1]++] + 1;
57         ans = max(ans, i - tmp + 1);
58     }
59     printf("%d\n", ans);
60     return 0;
61 }