zoj 3735 dp+计算几何

  1 #include<cstdio>
  2 #include<iostream>
  3 #include<algorithm>
  4 #include<cstring>
  5 #include<cmath>
  6 #include<queue>
  7 #include<map>
  8 using namespace std;
  9 #define MOD 1000000007
 10 const int INF=0x3f3f3f3f;
 11 const double eps=1e-5;
 12 typedef long long ll;
 13 #define cl(a) memset(a,0,sizeof(a))
 14 #define ts printf("*****\n");
 15 const int MAXN=310;
 16 int n,m;
 17 int sgn(double x)
 18 {
 19 if(fabs(x) < eps)return 0;
 20 if(x < 0)return -1;
 21 else return 1;
 22 }
 23 struct Point
 24 {
 25     int x,y;
 26     Point(){}
 27 Point(double _x,double _y)
 28 {
 29 x = _x;y = _y;
 30 }
 31 Point operator -(const Point &b)const
 32 {
 33 return Point(x - b.x,y - b.y);
 34 }
 35 //叉积
 36 double operator ^(const Point &b)const
 37 {
 38 return x*b.y - y*b.x;
 39 }
 40 //点积
 41 double operator *(const Point &b)const
 42 {
 43 return x*b.x + y*b.y;
 44 }
 45 //绕原点旋转角度B（弧度值），后x,y的变化
 46 };
 47 Point list[MAXN];
 48 int Stack[MAXN],top;
 49 double dist(Point a,Point b)
 50 {
 51     return sqrt((a-b)*(a-b));
 52 }
 53 //相对于list[0]的极角排序
 54 bool _cmp(Point p1,Point p2)
 55 {
 56     double tmp=(p1-list[0])^(p2-list[0]);
 57     if(sgn(tmp)>0)return true;
 58     else if(sgn(tmp)==0 && sgn(dist(p1,list[0]) - dist(p2,list[0])) <= 0)
 59     return true;
 60     else return false;
 61 }
 62 void Graham(int n)
 63 {
 64     Point p0;
 65     int k=0;
 66     p0=list[0];
 67     //找最下边的一个点
 68     for(int i=1;i < n;i++)
 69     {
 70         if( (p0.y>list[i].y) || (p0.y==list[i].y && p0.x>list[i].x) )
 71         {
 72             p0=list[i];
 73             k=i;
 74         }
 75     }
 76     swap(list[k],list[0]);
 77     sort(list+1,list+n,_cmp);
 78     if(n==1)
 79     {
 80         top=1;
 81         Stack[0]=0;
 82         return;
 83     }
 84     if(n==2)
 85     {
 86         top=2;
 87         Stack[0]=0;
 88         Stack[1]=1;
 89         return ;
 90     }
 91     Stack[0]=0;
 92     Stack[1]=1;
 93     top=2;
 94     for(int i=2;i < n;i++)
 95     {
 96         while(top>1 && sgn((list[Stack[top-1]]-list[Stack[top-2]])^(list[i]-list[Stack[top-2]])) <= 0)
 97         top--;
 98         Stack[top++]=i;
 99     }
100 }
101 int cost[MAXN][MAXN];
102 int dis(Point p1,Point p2)//计算题目定义的cost
103 {
104     return abs(p1.x+p2.x)*abs(p1.y+p2.y)%m;
105 }
106 int dp[MAXN][MAXN];
107 int main()
108 {
109     int i,j,k;
110     #ifndef ONLINE_JUDGE
111     freopen("1.in","r",stdin);
112     #endif
113     while(~scanf("%d%d",&n,&m))
114     {
115         for(i=0;i<n;i++)
116         {
117             scanf("%d%d",&list[i].x,&list[i].y);
118         }
119         Graham(n);
120         if(top!=n)
121         {
122             puts("I can‘t cut.");
123             continue;
124         }
125         cl(cost);
126         for(i=0;i<n;i++)
127             for(j=i+2;j<n;j++)
128                 cost[i][j]=cost[j][i]=dis(list[i],list[j]);
129         for(i=0;i<n;i++)
130         {
131             for(j=i;j<n;j++)dp[i][j]=INF;
132             dp[i][(i+1)%n]=0;
133         }
134         for(i=n-3;i>=0;i--)
135         {
136             for(j=i+2;j<n;j++)
137             {
138                 for(k=i+1;k<=j-1;k++)
139                 {
140                     dp[i][j]=min(dp[i][j],dp[i][k]+dp[k][j]+cost[i][k]+cost[k][j]);
141                 }
142             }
143         }
144         printf("%d\n",dp[0][n-1]);
145     }
146 }