POJ1661 Help Jimmy —— DP

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <cmath>
 5 #include <algorithm>
 6 #include <vector>
 7 #include <queue>
 8 #include <stack>
 9 #include <map>
10 #include <string>
11 #include <set>
12 #define ms(a,b) memset((a),(b),sizeof((a)))
13 using namespace std;
14 typedef long long LL;
15 const double EPS = 1e-8;
16 const int INF = 2e9;
17 const LL LNF = 2e18;
18 const int MAXN = 1e3+10;
19 
20 struct node
21 {
22     int l, r, h;
23     bool operator<(const node &x) const{
24         return h>x.h;
25     }
26 }a[MAXN];
27 int dp[MAXN][2];
28 
29 int main()
30 {
31     int T, n, x, y, mh;
32     scanf("%d", &T);
33     while(T--)
34     {
35         scanf("%d%d%d%d", &n,&x,&y,&mh);
36         for(int i = 1; i<=n; i++)
37             scanf("%d%d%d", &a[i].l, &a[i].r, &a[i].h);
38         a[++n].l = a[n].r = x; a[n].h = y;
39 
40         sort(a+1, a+1+n);
41         for(int i = 1; i<=n; i++)
42             dp[i][0] = dp[i][1] = INF;
43 
44         int ans = INF;
45         dp[1][0] = dp[1][1] = 0;
46         for(int i = 1; i<=n; i++)
47         {
48             if(dp[i][0]==INF) continue;
49             bool left = false, right = false;
50             for(int j = i+1; j<=n; j++)
51             {
52                 int dis_h = a[i].h - a[j].h;
53                 if(dis_h>mh) break;
54                 if(!left  && a[j].l<=a[i].l && a[i].l<=a[j].r )
55                 {
56                     left = true;
57                     dp[j][0] = min(dp[j][0], dp[i][0] + dis_h + a[i].l-a[j].l);
58                     dp[j][1] = min(dp[j][1], dp[i][0] + dis_h + a[j].r-a[i].l);
59                 }
60                 if(!right  && a[j].l<=a[i].r && a[i].r<=a[j].r )
61                 {
62                     right = true;
63                     dp[j][0] = min(dp[j][0], dp[i][1] + dis_h + a[i].r-a[j].l);
64                     dp[j][1] = min(dp[j][1], dp[i][1] + dis_h + a[j].r-a[i].r);
65                 }
66 
67                 if(left && right) break;
68             }
69 
70             if(a[i].h<=mh)
71             {
72                 if(!left) ans = min(ans, dp[i][0]+a[i].h);
73                 if(!right) ans = min(ans, dp[i][1]+a[i].h);
74             }
75         }
76 
77         printf("%d\n", ans);
78     }
79 }