Code:
#include<bits/stdc++.h> #define ll long long #define maxn 200000 #define inf 100000000000000 #define lson (t[x].ch[0]) #define rson (t[x].ch[1]) #define mid ((l+r)>>1) using namespace std; void debug() { printf("no_problem\n"); } int n,K,d,root; void setIO(string s) { string in=s+".in"; freopen(in.c_str(),"r",stdin); } priority_queue<ll,vector<ll>, greater<ll> >Q; struct Node { int p[2],ch[2],minv[2],maxv[2]; }t[maxn],T; bool cmp(Node a,Node b) { return a.p[d]==b.p[d]?a.p[d^1]<b.p[d^1]:a.p[d]<b.p[d]; } void pushup(int x,int y) { t[x].minv[0]=min(t[x].minv[0],t[y].minv[0]); t[x].maxv[0]=max(t[x].maxv[0],t[y].maxv[0]); t[x].minv[1]=min(t[x].minv[1],t[y].minv[1]); t[x].maxv[1]=max(t[x].maxv[1],t[y].maxv[1]); } int build(int l,int r,int o) { d=o; nth_element(t+l,t+mid,t+1+r,cmp); t[mid].minv[0]=t[mid].maxv[0]=t[mid].p[0]; t[mid].minv[1]=t[mid].maxv[1]=t[mid].p[1]; t[mid].ch[0]=t[mid].ch[1]=0; if(mid>l) { t[mid].ch[0]=build(l,mid-1,o^1); pushup(mid,t[mid].ch[0]); } if(r>mid) { t[mid].ch[1]=build(mid+1,r,o^1); pushup(mid,t[mid].ch[1]); } return mid; } ll sq(ll x) { return x * x; } ll getmax(int x) { ll ans=0; for(int i=0;i<2;++i) { ans+=max( sq(1ll*(t[x].minv[i]-T.p[i])), sq(1ll*(t[x].maxv[i]-T.p[i])) ); } return ans; } void solve(int x,int x1,int y1) { ll dn=getmax(x), cur=sq(1ll*(t[x].p[0]-x1)) + sq(1ll*(t[x].p[1]-y1)); if(dn <= Q.top()) return; if(cur>Q.top()) { Q.pop(); Q.push(cur); } ll dl=lson ? getmax(lson) : -inf; ll dr=rson ? getmax(rson) : -inf; if(dl>dr) { if(dl > Q.top()) solve(lson, x1, y1); if(dr > Q.top()) solve(rson, x1, y1); } else { if(dr > Q.top()) solve(rson, x1, y1); if(dl > Q.top()) solve(lson, x1, y1); } } int main() { // setIO("input"); scanf("%d%d",&n,&K); K<<=1; for(int i=1;i<=n;++i) scanf("%d%d",&t[i].p[0],&t[i].p[1]); root=build(1,n,0); for(int i=1;i<=K;++i) Q.push(0); for(int i=1;i<=n;++i) { T.p[0]=t[i].p[0]; T.p[1]=t[i].p[1]; solve(root,T.p[0],T.p[1]); } printf("%lld\n",Q.top()); return 0; }