108 lines
2.8 KiB
C++
108 lines
2.8 KiB
C++
#include <vector>
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#include <cmath>
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#include <cstdio>
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#include <string>
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#include <cstring>
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#include <iostream>
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#include <algorithm>
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#define MAXN 10010
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#define LL long long
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using namespace std;
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bool vis[MAXN][MAXN];
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struct DOT {
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int x, y;
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DOT() {}
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DOT(int _x, int _y) {
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x = _x; y = _y;
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}
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}dot[MAXN];
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struct Matrix {
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DOT up, down;
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Matrix() { }
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Matrix(DOT a, DOT b) {
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up = a;
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down = b;
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}
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}maxrix[MAXN];
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int area(Matrix m) {
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return (m.down.x-m.up.x)*(m.up.y-m.down.y);
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}
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vector<Matrix> vec;
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bool cmp(DOT a, DOT b) {
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if(a.x < b.x)
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return true;
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if(a.x > b.x)
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return false;
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return a.y <= b.y;
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}
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int son_judge(DOT t, Matrix m) {
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int x1 = m.up.x;
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int y1 = m.up.y;
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int x2 = m.down.x;
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int y2 = m.down.y;
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if(t.x>=x1 && t.x<=x2 && t.y<=y1 && t.y>=y2) {
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if(t.x>x1 && t.x<x2 && t.y<y1 && t.y>y2)
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return 1;
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return 0;
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}
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return -1;
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}
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int judge(int i, int j) {
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DOT t1 = DOT(vec[i].up.x, vec[i].down.y);
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DOT t2 = DOT(vec[i].down.x, vec[i].up.y);
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int ok1 = son_judge(vec[i].up, vec[j]);
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int ok2 = son_judge(vec[i].down, vec[j]);
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int ok3 = son_judge(t1, vec[j]);
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int ok4 = son_judge(t2, vec[j]);
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if(ok1==1&&ok2==1&&ok3==1&&ok4==1)
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return 1;
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if(ok1==-1&&ok2==-1&&ok3==-1&&ok4==-1)
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return -1;
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return 0;
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}
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int main() {
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int n;
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while(scanf("%d", &n) && n) {
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if(n < 8) {
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puts("imp");
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continue;
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}
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vec.clear();
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memset(vis, 0, sizeof(vis));
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for(int i=0; i<n; ++i) {
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scanf("%d%d", &dot[i].x, &dot[i].y);
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vis[dot[i].x][dot[i].y] = true;
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}
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sort(dot, dot+n, cmp);
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int x1, x2, y1, y2;
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for(int i=0; i<n; ++i) {
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x1 = dot[i].x;
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y1 = dot[i].y;
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for(int j=i+1; j<n; ++j) {
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x2 = dot[j].x;
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y2 = dot[j].y;
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if(x2<=x1 || y2>=y1) continue;
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if(vis[x2][y1] && vis[x1][y2]) {
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vec.push_back(Matrix(dot[i], dot[j]));
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}
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}
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}
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int ans = 0;
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for(int i=0; i<vec.size(); ++i) {
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for(int j=i+1; j<vec.size(); ++j) {
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int tmp1 = judge(i, j);
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int tmp2 = judge(j, i);
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if(tmp1 == 1 || tmp2 == 1) {
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ans = max(ans, max(area(vec[i]), area(vec[j])));
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} else if(tmp1 == -1 && tmp2 == -1) {
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ans = max(ans, area(vec[i])+area(vec[j]));
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}
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}
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}
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if(ans == 0)
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puts("imp");
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else printf("%d\n", ans);
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}
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return 0;
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}
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