http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemCode=3537
学会了求凸包 其实就是单调栈的思想 详见https://blog.csdn.net/codeswarrior/article/details/81327277
然后就是裸的凸多边形三角划分 区间DP即可
#include <bits/stdc++.h>
using namespace std;
const int maxn=3e2+10;
struct node
{
int x,y;
};
node stk[maxn];
node point[maxn],pre[maxn],suf[maxn];
int dp[maxn][maxn],cost[maxn][maxn];
int n,m,top,n1,n2;
bool cmp(node n1,node n2)
{
if(n1.x==n2.x) return n1.y>n2.y;
else return n1.x<n2.x;
}
int cmpk(node p1,node p2,node p3)
{
return (p2.y-p1.y)*(p3.x-p1.x)>(p3.y-p1.y)*(p2.x-p1.x);
}
bool judge()
{
node cur1,cur2;
int i;
top=0;
stk[++top]=point[1],stk[++top]=point[2];
for(i=3;i<=n;i++){
while(top>=2&&cmpk(stk[top-1],stk[top],point[i])) top--;
stk[++top]=point[i];
}
for(i=1;i<=top;i++) pre[i]=stk[i];
n1=top;
//for(i=1;i<=n1;i++) printf("*%d %d*\n",pre[i].x,pre[i].y);
top=0;
stk[++top]=point[n],stk[++top]=point[n-1];
for(i=n-2;i>=1;i--){
while(top>=2&&cmpk(stk[top-1],stk[top],point[i])) top--;
stk[++top]=point[i];
}
for(i=1;i<=top;i++) suf[i]=stk[i];
n2=top;
//for(i=1;i<=n2;i++) printf("*%d %d*\n",suf[i].x,suf[i].y);
if(n1+n2-2<n) return 0;
else{
n=0;
for(i=1;i<=n1;i++){
point[++n]=pre[i];
}
for(i=2;i<=n2-1;i++){
point[++n]=suf[i];
}
return 1;
}
}
int getval(node p1,node p2)
{
return abs(p1.x+p2.x)*abs(p1.y+p2.y)%m;
}
int main()
{
int i,j,k,l;
while(scanf("%d%d",&n,&m)!=EOF){
for(i=1;i<=n;i++){
scanf("%d%d",&point[i].x,&point[i].y);
}
sort(point+1,point+n+1,cmp);
if(judge()){
//for(i=1;i<=n;i++) printf("*%d %d*\n",point[i].x,point[i].y);
memset(dp,0x3f,sizeof(dp));
for(i=1;i+1<=n;i++) dp[i][i+1]=0;
memset(cost,0,sizeof(cost));
for(i=1;i<=n;i++){
for(j=i+2;j<=n;j++){
cost[i][j]=getval(point[i],point[j]);
}
}
for(l=3;l<=n;l++){
for(i=1;i+l-1<=n;i++){
j=i+l-1;
//printf("***%d %d***\n",i,j);
for(k=i+1;k<=j-1;k++){
dp[i][j]=min(dp[i][j],dp[i][k]+dp[k][j]+cost[i][k]+cost[k][j]);
}
}
}
printf("%d\n",dp[1][n]);
}
else printf("I can't cut.\n");
}
return 0;
}
/*
4 100000
1 2
3 1
4 2
2 3
*/