Brief description:
略。）
Analysis:
老套路。。虽然题目保证 32-int。。。但是实际还是有一些危险的（？）。
。全程 LL 居然会 TLE。=_=）
//}/* .................................................................................................................................. */
const int N = int(1e4) + 9;
int _f[2][N], *f = _f[0], *ff = _f[1]; int A[N]; int q[N], cz, op;
int n, m;
#define k (-2*A[i])
#define x(j) (A[j+1])
#define y(j) (ff[j] + sqr(x(j)))
#define eval(j) (k*x(j) + y(j))
LL det(LL x1, LL y1, LL x2, LL y2){
return x1*y2 - x2*y1;
}
int dett(int p0, int p1, int p2){
LL t = det(x(p1)-x(p0), y(p1)-y(p0), x(p2)-x(p0), y(p2)-y(p0));
return t < 0 ? -1 : t > 0;
}
int main(){
#ifndef ONLINE_JUDGE
freopen("in.txt", "r", stdin);
//freopen("out.txt", "w", stdout);
#endif
Rush{
RD(n, m); REP_1(i, n) RD(A[i]); sort(A+1, A+n+1);
REP_1(i, n) f[i] = sqr(A[i] - A[1]);
DO(m-1){
swap(f, ff); cz = 0, op = -1; REP_1(i, n){
while (cz < op && dett(q[op-1], q[op], i) <= 0) --op; q[++op] = i;
while (cz < op && eval(q[cz]) >= eval(q[cz+1])) ++cz; f[i] = sqr(A[i]) + eval(q[cz]);
}
}
OT(f[n]);
}
}
http://acm.hust.edu.cn/vjudge/problem/viewSource.action?id=2801201
