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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 |
---|---|---|---|---|---|---|---|---|---|
#298750 | #7906. Almost Convex | ucup-team918# | WA | 7ms | 3908kb | C++17 | 2.5kb | 2024-01-06 14:29:47 | 2024-01-06 14:29:48 |
Judging History
answer
#include <bits/stdc++.h>
using namespace std;
#define int long long
const double pi = acos(-1);
int n, vis[2010];
pair<int, int> a[2010];
double val[2010];
int calc(pair<int, int> i, pair<int, int> j, pair<int, int> k) {
return (j.first - i.first) * (k.second - i.second) - (j.second - i.second) * (k.first - i.first);
}
signed main() {
ios::sync_with_stdio(false);
cin.tie(0), cout.tie(0);
cin >> n;
for (int i = 1; i <= n; i++)
cin >> a[i].first >> a[i].second;
sort(a + 1, a + n + 1);
vector<int> u, d, p;
u.push_back(1), d.push_back(1);
for (int i = 2; i <= n; i++) {
while (u.size() > 1) {
int j = u.back(), k = u[u.size() - 2];
if (calc(a[k], a[j], a[i]) > 0) u.pop_back();
else break;
}
u.push_back(i);
while (d.size() > 1) {
int j = d.back(), k = d[d.size() - 2];
if (calc(a[k], a[j], a[i]) < 0) d.pop_back();
else break;
}
d.push_back(i);
}
for (int x : u) vis[x] = 1;
for (int x : d) vis[x] = 1;
for (int i = 1; i <= n; i++)
if (!vis[i]) p.push_back(i);
int ans = 1;
for (int i = 1; i < d.size(); i++) {
int o = d[i - 1], v = d[i];
double t = atan2(a[v].second - a[o].second, a[v].first - a[o].first);
for (int x : p) {
val[x] = atan2(a[x].second - a[o].second, a[x].first - a[o].first);
val[x] -= t;
if (val[x] < 0) val[x] += pi * 2;
}
sort(p.begin(), p.end(), [&](int x, int y) {
return val[x] > val[y];
});
stack<int> st;
for (int x : p) {
while (!st.empty()) {
int y = st.top();
if (calc(a[o], a[y], a[x]) > 0 && calc(a[v], a[x], a[y]) > 0)
st.pop();
else break;
}
if (!st.empty()) {
int y = st.top();
if (calc(a[o], a[x], a[y]) > 0 && calc(a[v], a[y], a[x]) > 0)
continue;
}
st.push(x);
}
ans += st.size();
}
for (int i = 1; i < u.size(); i++) {
int o = u[i], v = u[i - 1];
double t = atan2(a[v].second - a[o].second, a[v].first - a[o].first);
for (int x : p) {
val[x] = atan2(a[x].second - a[o].second, a[x].first - a[o].first);
val[x] -= t;
if (val[x] < 0) val[x] += pi * 2;
}
sort(p.begin(), p.end(), [&](int x, int y) {
return val[x] > val[y];
});
stack<int> st;
for (int x : p) {
while (!st.empty()) {
int y = st.top();
if (calc(a[o], a[y], a[x]) > 0 && calc(a[v], a[x], a[y]) > 0)
st.pop();
else break;
}
if (!st.empty()) {
int y = st.top();
if (calc(a[o], a[x], a[y]) > 0 && calc(a[v], a[y], a[x]) > 0)
continue;
}
st.push(x);
}
ans += st.size();
}
cout << ans << endl;
return 0;
}
详细
Test #1:
score: 100
Accepted
time: 1ms
memory: 3856kb
input:
7 1 4 4 0 2 3 3 1 3 5 0 0 2 4
output:
9
result:
ok 1 number(s): "9"
Test #2:
score: 0
Accepted
time: 0ms
memory: 3856kb
input:
5 4 0 0 0 2 1 3 3 3 1
output:
5
result:
ok 1 number(s): "5"
Test #3:
score: 0
Accepted
time: 1ms
memory: 3860kb
input:
3 0 0 3 0 0 3
output:
1
result:
ok 1 number(s): "1"
Test #4:
score: 0
Accepted
time: 0ms
memory: 3848kb
input:
6 0 0 3 0 3 2 0 2 1 1 2 1
output:
7
result:
ok 1 number(s): "7"
Test #5:
score: 0
Accepted
time: 1ms
memory: 3736kb
input:
4 0 0 0 3 3 0 3 3
output:
1
result:
ok 1 number(s): "1"
Test #6:
score: -100
Wrong Answer
time: 7ms
memory: 3908kb
input:
2000 86166 617851 383354 -277127 844986 386868 -577988 453392 -341125 -386775 -543914 -210860 -429613 606701 -343534 893727 841399 339305 446761 -327040 -218558 -907983 787284 361823 950395 287044 -351577 -843823 -198755 138512 -306560 -483261 -487474 -857400 885637 -240518 -297576 603522 -748283 33...
output:
18950
result:
wrong answer 1st numbers differ - expected: '718', found: '18950'