BZOJ2216 [Poi2011]Lightning Conductor

Orz ydc："这题是我见到的第一道非斜率优化的1D1D了……"

话说ydc神犇认为单调队列不是优化咩？、、、已经给跪了

Orz决策单调性

 

 1 /**************************************************************
 2     Problem: 2216
 3     User: rausen
 4     Language: C++
 5     Result: Accepted
 6     Time:4128 ms
 7     Memory:16432 kb
 8 ****************************************************************/
 9  
10 #include <cstdio>
11 #include <cmath>
12 #include <algorithm>
13  
14 using namespace std;
15 typedef double lf;
16 const int N = 500005;
17  
18 struct data {
19     int l, r, p;
20     data() {}
21     data(int _l, int _r, int _p) : l(_l), r(_r), p(_p) {}
22 }q[N];
23  
24 int n, a[N];
25 lf f[N], g[N];
26  
27 inline int read() {
28     int x = 0, sgn = 1;
29     char ch = getchar();
30     while (ch < '0' || '9' < ch) {
31         if (ch == '-') sgn = -1;
32         ch = getchar();
33     }
34     while ('0' <= ch && ch <= '9') {
35         x = x * 10 + ch - '0';
36         ch = getchar();
37     }
38     return sgn * x;
39 }
40  
41 inline lf calc(int j, int i) {
42     return a[j] - a[i] + sqrt(abs(i - j));
43 }
44  
45 int find(data t, int x) {
46     int l = t.l, r = t.r, mid;
47     while (l <= r) { 
48         mid = l + r >> 1;
49         if (calc(t.p, mid) > calc(x, mid))
50             l = mid + 1;
51         else r = mid - 1;
52     }
53     return l;
54 }
55  
56 void dp(lf *F) {
57     for (int i = 1, h = 1, t = 0, tmp; i <= n; ++i) {
58         ++q[h].l;
59         if (h <= t && q[h].r < q[h].l) ++h;
60         if (h > t || calc(i, n) > calc(q[t].p, n)) {
61             while (h <= t && calc(q[t].p, q[t].l) < calc(i, q[t].l))
62                 --t;
63             if (h > t) q[++t] = data(i, n, i);
64             else {
65                 tmp = find(q[t], i);
66                 q[t].r = tmp - 1;
67                 q[++t] = data(tmp, n, i);
68             }
69         }
70         F[i] = calc(q[h].p, i);
71     }
72 }
73  
74 int main() {
75     int i;
76     n = read();
77     for (i = 1; i <= n; ++i)
78         a[i] = read();
79     dp(f);
80     reverse(a + 1, a + n + 1);
81     dp(g);
82     for (i = 1; i <= n; ++i)
83         printf("%d\n", (int) ceil(max(f[i], g[n - i + 1])));
84     return 0;
85 }
86
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posted on 2014-11-29 17:17  Xs酱~  阅读(251)  评论(0)  编辑  收藏  举报