Submission #33799130

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
#define MOD 1000000007
#define rep(i,a,n) for (ll i=a;i<(ll)n;i++)
#define per(i,a,n) for (ll i=n;i-->(ll)a;)
#define pb push_back

ll read(){ll r;scanf("%lld",&r);return r;} // read

ll gcd(ll a,ll b){
  a = abs(a);
  b = abs(b);
  while(b!= 0) tie(a,b) = make_pair(b,a%b);
  return a;
}
const ll INF = 0x3f3f3f3f3f3f3f3f;
array<ll,3> xyv[1010];
map<tuple<ll,ll,ll>, vector<pair<int,int> > > cx;

void addp(int i,int j){
  auto [x0,y0,v0] = xyv[i];
  auto [x1,y1,v1] = xyv[j];
  // 对称轴, 标准化
  ll ky = 2*(y1-y0);
  ll kx = -2*(x1-x0);
  ll k  = (x1-x0)*(x1+x0) + (y1-y0)*(y1+y0);
  ll g = gcd(k,gcd(ky,kx));
  ky /= g;
  kx /= g;
  k  /= g;
  if(ky < 0){
    ky = -ky;
    kx = -kx;
    k  = -k;
  }else if(ky == 0 && kx < 0){
    kx = -kx;
    k  = -k;
  }
  cx[{ky,kx,k}].push_back({i,j});
}

int main(){
  int n = read();
  rep(i,0,n){
    int x = read();
    int y = read();
    int v = read();
    xyv[i] = {x,y,v};
  }
  rep(i,0,n) rep(j,i+1,n) addp(i,j);
  ll ans = -1;
  for(auto [_,vec]:cx){
    auto center = [=](const pair<int,int>&ij){
        auto [i0,j0] = ij;
        auto [x0,y0,v0] = xyv[i0];
        auto [x1,y1,v1] = xyv[j0];
        return make_pair(x0+x1,y0+y1);
    };
    sort(vec.begin(),vec.end(), [=](const auto &ij0,const auto &ij1){
        return center(ij0) < center(ij1);
    });
    ll lastmax = -INF;
    ll cur = -INF;
    rep(i,0,vec.size()){
      if(i == 0 || center(vec[i]) != center(vec[i-1])){
        lastmax = max(lastmax,cur);
        cur = 0;
      }
      auto [i0,j0] = vec[i];
      cur = max(cur, xyv[i0][2] + xyv[j0][2]);
      if(lastmax != -INF){
        ans = max(ans, lastmax + cur);
      }
    }
  }
  printf("%lld\n",ans);
  return 0;
}

// y = -(x1-x0)/(y1-y0) (x - (x0+x1)/2) + (y0+y1)/2
// 2(y1-y0) y = -2(x1-x0) x + (x1-x0)(x1+x0) + (y0+y1)(y1-y0)

Submission Info

Compile Error

./Main.cpp: In function ‘ll read()’:
./Main.cpp:10:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
   10 | ll read(){ll r;scanf("%lld",&r);return r;} // read
      |                ~~~~~^~~~~~~~~~~

Judge Result