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Cod sursa(job #1130547)
Utilizator | Data | 28 februarie 2014 13:55:49 | |
---|---|---|---|
Problema | Oypara | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Lista lui wefgef | Marime | 1.92 kb |
#include <stdio.h>
#include <algorithm>
using namespace std;
struct point {
int x, y;
point() {
x = y = 0;
}
point(int xx, int yy) {
x = xx; y = yy;
}
} up[100100], down[100100], hup[100100], hdown[100100];
int ccw(point A, point B, point C) {
long long cross = ((long long)B.x - A.x) * (C.y - B.y) - ((long long)B.y - A.y) * (C.x - B.x);
return cross <= 0;
}
inline bool comp1(point A, point B) {
if (A.x == B.x)
return A.y < B.y;
return A.x < B.x;
}
inline bool comp2(point A, point B) {
if (A.x == B.x)
return A.y > B.y;
return A.x > B.x;
}
void convexHull(point x[], point hull[], int type, int &cnt, int n) {
if (type == 0)
sort(x + 1, x + n + 1, comp1);
else
sort(x + 1, x + n + 1, comp2);
hull[++cnt] = x[1]; hull[++cnt] = x[2];
for (int i = 3; i <= n; ++i) {
while (cnt > 1 && ccw(hull[cnt - 1], hull[cnt], x[i]))
--cnt;
hull[++cnt] = x[i];
}
}
int main() {
freopen("oypara.in", "r", stdin);
freopen("oypara.out", "w", stdout);
int n;
scanf("%d", &n);
for (int i = 1; i <= n; ++i) {
int x, yup, ydown;
scanf("%d%d%d", &x, &ydown, &yup);
up[i] = point(x, yup);
down[i] = point(x, ydown);
}
int upCnt = 0, downCnt = 0;
convexHull(up, hup, 0, upCnt, n);
convexHull(down, hdown, 1, downCnt, n);
point solUp, solDown;
for (int i = 1, j = 1; i < upCnt; ++i) {
for (; ccw(hup[i], hup[i + 1], hdown[j]) && j <= downCnt; ++j);
if (j == downCnt + 1) {
solUp = hup[i];
break;
}
}
for (int i = 1; i < downCnt; ++i)
if (ccw(hdown[i], hdown[i + 1], solUp)) {
solDown = hdown[i];
break;
}
printf("%d %d %d %d", solUp.x, solUp.y, solDown.x, solDown.y);
return 0;
}