这种简单的斜率都写不明白了Harbin regional hdu3669

我的假期基本残废了= =！尼玛做管理员太累了……自己的训练基本停滞了……提高太少了，我的梦想还能实现吗……

贴的代码完事吧

HDU 3669

 1 #include <iostream>
 2 #include <cstring>
 3 #include <cstdio>
 4 #include <algorithm>
 5 using namespace std;
 6 typedef long long LL;
 7 const int N = 500011, K = 101;
 8 LL dp[K][N];
 9 int q[N], head, tail;
10 struct person
11 {
12     int h, w;
13     bool operator < (const person& a)const
14     {
15         return h == a.h ? w < a.w : h > a.h;
16     }
17 } persons[N];
18 LL DP(int n, int m)
19 {
20     head = tail = 0;
21     for(int i = 1; i <= n; i++)
22     {
23         dp[1][i] = 1ll * persons[i].w * persons[1].h;
24     }
25     for(int j = 2; j <= m; j++)
26     {
27         head = tail = 0;
28         q[tail++] = j - 1;
29         for(int i = j;i <= n; i++)
30         {
31             while(head + 1 < tail)
32             {
33                 int p1 = q[head], p2 = q[head + 1];
34                 LL y1 = dp[j - 1][p1], y2 = dp[j - 1][p2];
35                 LL x1 = persons[p1 + 1].h, x2 = persons[p2 + 1].h;
36                 if(y1 - y2 + persons[i].w * (x1 - x2) >= 0)
37                     head++;
38                 else
39                     break;
40             }
41             int p = q[head];
42             dp[j][i] = dp[j - 1][p] + 1ll * persons[p + 1].h * persons[i].w;
43             while(head + 1 < tail)
44             {
45                 int p1 = q[tail - 2], p2 = q[tail - 1], p3 = i;
46                 LL y1 = dp[j - 1][p1], y2 = dp[j - 1][p2], y3 = dp[j - 1][p3];
47                 LL x1 = persons[p1 + 1].h, x2 = persons[p2 + 1].h, x3 = persons[p3 + 1].h;
48                 if((y1 - y2) * (x2 - x3) > (y2 - y3) * (x1 - x2))
49                     break;
50                 else
51                     tail--;
52             }
53             q[tail++] = i;
54         }
55     }
56     LL ret = dp[1][n];
57     for(int i = 2;i <= m;i++)
58         ret = min(ret, dp[i][n]);
59     return ret;
60 }
61 int main()
62 {
63     int n, m;
64     while(scanf("%d %d", &n, &m) == 2)
65     {
66         for(int i = 1; i <= n; i++)
67             scanf("%d%d",&persons[i].w, &persons[i].h);
68         sort(persons + 1, persons + n + 1);
69         int i = 1, j = 0;
70         for(; i <= n; i++)
71         {
72             if(j == 0 || persons[i].w > persons[j].w)
73                 persons[++j] = persons[i];
74         }
75         cout <<  DP(j, m) << endl;
76     }
77     return 0;
78 }