QOJ.ac
QOJ
ID | 题目 | 提交者 | 结果 | 用时 | 内存 | 语言 | 文件大小 | 提交时间 | 测评时间 |
---|---|---|---|---|---|---|---|---|---|
#730595 | #9520. Concave Hull | silver_muse | AC ✓ | 74ms | 13368kb | C++20 | 3.1kb | 2024-11-09 20:46:29 | 2024-11-09 20:46:31 |
Judging History
answer
#include<bits/stdc++.h>
using namespace std;
typedef long long i64;
struct point {
i64 x, y;
point(i64 x = 0, i64 y = 0): x(x), y(y) {}
i64 hval() {return ((x + 1000000000LL) << 31) | (y + 1000000000LL);}
};
struct arrow {
i64 x, y;
arrow(i64 x = 0, i64 y = 0): x(x), y(y) {}
arrow(point a, point b): x(b.x - a.x), y(b.y - a.y) {}
};
bool operator == (const point &a, const point &b) {
return a.x == b.x && a.y == b.y;
}
bool operator < (const point &a, const point &b) {
if(a.x == b.x) return a.y < b.y;
else return a.x < b.x;
}
i64 dot(const arrow &a, const arrow &b) {
return a.x * b.x + a.y * b.y;
}
i64 cross(const arrow &a, const arrow &b) {
return a.x * b.y - a.y * b.x;
}
// 三角形面积的两倍
i64 area(const point &a, const point &b, const point &c) {
return abs(cross({a, b}, {a, c}));
}
// 将参数 v 变成一个凸包,逆时针排序,v[0] 是坐标最小的点
void makeConvex(vector<point> &v) {
sort(v.begin(), v.end());
v.erase(unique(v.begin(), v.end()), v.end());
vector<point> t;
for(int cnt = 0; cnt < 2; cnt++) {
reverse(v.begin(), v.end());
stack<point> p; stack<arrow> e;
p.push(v[0]);
for(int i = 1; i < v.size(); i++) {
// 下面这个 while 会导致凸包上任意三个点都不在同一个直线上
// 如果需要保留凸包边中间的点,把 >= 改成 > 即可
while(!e.empty() && cross(e.top(), {p.top(), v[i]}) >= 0)
p.pop(), e.pop();
e.push(arrow(p.top(), v[i]));
p.push(v[i]);
}
while(p.size() > 1)
t.push_back(p.top()), p.pop();
}
v = t;
}
void solve() {
i64 n, ans = 0, mint = 8e18; cin >> n;
vector<point> v, t, temp;
unordered_set<i64> mp;
for(int i = 1; i <= n; i++) {
i64 x, y; cin >> x >> y;
v.push_back({x, y});
temp.push_back({x, y});
}
makeConvex(v); v.push_back(v[0]);
for(int i = 1; i < v.size(); i++) {
ans += area(v[0], v[i], v[i - 1]);
}
for(auto p : v) {
mp.insert(p.hval());
}
for(auto p : temp) {
if(!mp.count(p.hval())) t.push_back(p);
}
if(t.size() == 0) {cout << "-1" << endl; return;}
else if(t.size() < 3) {
for(auto p : t) for(int i = 1; i < v.size(); i++)
mint = min(mint, area(p, v[i], v[i - 1]));
cout << ans - mint << endl;
} else {
makeConvex(t); int szt = t.size(), p = 0;
for(int i = 0; i < szt * 2; i++) {
t.push_back(t[i]);
}
for(int i = 0; i < szt; i++) {
if(area(v[0], v[1], t[i]) < area(v[0], v[1], t[p])) p = i;
}
for(int i = 1; i < v.size(); i++) {
while(area(v[i], v[i - 1], t[p + 1]) <= area(v[i], v[i - 1], t[p])) p++;
mint = min(mint, area(v[i], v[i - 1], t[p]));
}
cout << ans - mint << endl;
}
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int T; cin >> T;
while(T--) solve();
return 0;
}
这程序好像有点Bug,我给组数据试试?
详细
Test #1:
score: 100
Accepted
time: 0ms
memory: 3640kb
input:
2 6 -2 0 1 -2 5 2 0 4 1 2 3 1 4 0 0 1 0 0 1 1 1
output:
40 -1
result:
ok 2 lines
Test #2:
score: 0
Accepted
time: 1ms
memory: 3596kb
input:
10 243 -494423502 -591557038 -493438474 -648991734 -493289308 -656152126 -491185085 -661710614 -489063449 -666925265 -464265894 -709944049 -447472922 -737242534 -415977509 -773788538 -394263365 -797285016 -382728841 -807396819 -373481975 -814685302 -368242265 -818267002 -344482838 -833805545 -279398...
output:
2178418010787347715 1826413114144932145 1651687576234220014 1883871859778998985 2119126281997959892 894016174881844630 2271191316922158910 1998643358049669416 1740474221286618711 1168195646932543192
result:
ok 10 lines
Test #3:
score: 0
Accepted
time: 33ms
memory: 3948kb
input:
1000 125 64661186 -13143076 302828013 -185438065 -418713797 -191594241 430218126 -397441626 354327250 -836704374 149668812 -598584998 311305970 66790541 199720625 -592356787 468137 -584752683 258775829 96211747 -358669612 -134890109 -129221188 -998432368 -277309896 -140056561 356901185 420557649 -51...
output:
1986320445246155278 1900093336073022078 1612088392301142476 2012259136539173407 1819942017252118749 1772230185841892196 1164835025329039520 1527446155241140517 1807368432185303666 1236918659444944569 1306839249967484778 1984123720246784099 1868728080720036006 667458140583450322 2127932992585026491 4...
result:
ok 1000 lines
Test #4:
score: 0
Accepted
time: 52ms
memory: 3620kb
input:
10000 9 484630042 51929469 -40468396 -517784096 98214104 -103353239 629244333 -475172587 106398764 153884485 49211709 -44865749 1 10 166321833 -247717657 406208245 668933360 13 548702216 -631976459 37150086 -292461024 707804811 -486185860 239775286 -903166050 10096571 -541890068 686103484 558731937 ...
output:
950319193795831919 1661025342421008544 1285164852091455548 1159924751776806668 1206071151805176722 794021230296144371 699991678992587791 1133990718508584290 1486311831172661605 984875884297072200 1327767982175057345 758247019006396699 1355381234262206155 1139262078529131471 1613462877860621700 12392...
result:
ok 10000 lines
Test #5:
score: 0
Accepted
time: 66ms
memory: 4392kb
input:
100 439 471536154 -312612104 155692036 -937312180 -461624056 -357636609 236656684 -911414873 -288656914 -74788431 -465779694 -381475149 -334197401 -903065737 491513067 -447615916 337664889 -852236281 -281689379 -53519178 -159101704 -920779200 -326159514 -95396204 21868593 -994282736 488425383 -41046...
output:
1973162724053130487 2054612790507830954 1726805687754843724 1699420177872986528 2129388571309147631 2198295137903288810 1697185883164440272 1219697450095721478 2027023581922285255 1674691247127206655 1673105966817209954 2179188692918747442 2146544318743443141 2230356305133660648 1676850321902993764 ...
result:
ok 100 lines
Test #6:
score: 0
Accepted
time: 51ms
memory: 4336kb
input:
100 1362 -467257672 -466669 -467054869 -478108 -466973270 -481776 -466556983 -499770 -466329414 -508693 -466248017 -511805 -466158865 -513786 -466101273 -515035 -465927700 -518748 -465717624 -522106 -465303448 -528127 -465124548 -530726 -464649746 -536693 -464554872 -537799 -464478196 -538680 -46416...
output:
1666097696993497 1791366071767866 1806187278469532 1683419854733713 1685891971828916 1730190225081651 1787048201197565 1850308098208660 1710694884375502 1826363113637639 1816375352374659 2047431269497691 1549806516003854 1829438662895747 1678707854135065 1687423392883819 2121960009997761 16687219538...
result:
ok 100 lines
Test #7:
score: 0
Accepted
time: 32ms
memory: 8336kb
input:
2 62666 -486101704 -505730259 -486101698 -506082699 -486101689 -506111362 -486101682 -506126031 -486101528 -506293759 -486101259 -506556385 -486101196 -506613483 -486101154 -506648604 -486100935 -506831392 -486100631 -507083675 -486100470 -507199151 -486100233 -507368923 -486100193 -507397039 -48609...
output:
2178736946152219010 1825181940245096152
result:
ok 2 lines
Test #8:
score: 0
Accepted
time: 62ms
memory: 11644kb
input:
2 100000 301945097 76373292 467957663 -286424714 8245445 -597212507 -474204621 -708828667 184159460 105942538 443435905 -429212625 490658771 -382198656 82512047 -612522436 -228221388 -965890088 394789011 -145801151 -106120174 -528202395 428939626 -194437311 497429477 -527407728 365739746 -114818962 ...
output:
2502889432701099511 2267250485735988121
result:
ok 2 lines
Test #9:
score: 0
Accepted
time: 74ms
memory: 13368kb
input:
2 100000 221128057 -975244780 -618765360 -785575858 422567455 -906331476 -988680318 -150037424 -929870145 367887908 -757813541 -652471177 291995621 -956419655 -785381507 619012026 468864522 -883270094 -588416522 808557973 859345881 511394814 988105866 153775152 216931298 -976186873 467050734 8842305...
output:
6283183114882825575 6283183188903854361
result:
ok 2 lines
Test #10:
score: 0
Accepted
time: 1ms
memory: 3836kb
input:
7 5 -1000000000 -1000000000 1000000000 -1000000000 1000000000 1000000000 1 0 -1 0 5 1000000000 1000000000 -1000000000 -1000000000 -2 0 -1 0 1 -1 6 1000000000 1000000000 -1000000000 -1000000000 -3 0 -1 0 0 -1 1 -1 4 -1000000000 -1000000000 1000000000 -1000000000 1000000000 1000000000 -1000000000 1000...
output:
4000000000000000000 7000000000 9000000001 -1 6000000002000000000 7999999998000000000 -1
result:
ok 7 lines
Extra Test:
score: 0
Extra Test Passed