QOJ.ac
QOJ
ID | Problem | Submitter | Result | Time | Memory | Language | File size | Submit time | Judge time |
---|---|---|---|---|---|---|---|---|---|
#487425 | #6352. SPPPSPSS. | ucup-team2307# | WA | 1ms | 3628kb | C++20 | 3.2kb | 2024-07-22 21:30:16 | 2024-07-22 21:30:19 |
Judging History
answer
#pragma GCC optimize("Ofast,unroll-loops")
#include<bits/stdc++.h>
#pragma GCC target("avx,avx2,sse,sse2")
#define all(x) begin(x), end(x)
using namespace std;
using ll = long long;
int solve(vector<int> p) {
int n = p.size();
vector<int> prefMax = p, sufMin = p, fixed(n);
for(int i = 1; i < n; i++)
prefMax[i] = max(prefMax[i - 1], p[i]);
for(int i = n - 1; i--;)
sufMin[i] = min(sufMin[i + 1], p[i]);
for(int i = 0; i < n; i++) {
fixed[i] = p[i] == i;
if(i) fixed[i] += fixed[i - 1];
}
vector<int> mid_p = p;
int mid_op = 1;
while(mid_op + (mid_op + 1) <= n) mid_op++;
{
int pref = mid_op, suf = mid_op;
pref -= mid_op%2 == 0;//must be odd
suf -= mid_op%2 == 1;//must be even
if(pref < mid_op) {//prefix first
sort(mid_p.begin(), mid_p.begin() + pref);
sort(mid_p.end() - suf, mid_p.end());
} else {//sufix first
sort(mid_p.end() - suf, mid_p.end());
sort(mid_p.begin(), mid_p.begin() + pref);
}
}
if(fixed.back() == n) return 0;
auto check = [&](int ops) -> bool {//PSPSPSPS
if(ops < 2) return 0;
// cout << "CHECK" << ops << endl;
int pref = ops, suf = ops;
pref -= ops%2 == 0;//must be odd
suf -= ops%2 == 1;//must be even
if(ops <= mid_op) {
int ok = 1;
// for(auto i : p) cout << i << " "; cout << endl;
ok &= prefMax[pref - 1] == (pref - 1);
ok &= sufMin[n - suf] == (n - suf);
// cout << prefMax[pref - 1] << " " << pref - 1 << " " << ok << endl;
// cout << sufMin[n - suf] << " " << n - suf << " " << ok << endl;
for(int i = pref + 1; i < n - suf; i++) ok &= p[i] == i;
// cout << pref << " " << suf << " " << ok << endl;
return ok;
}
int cut;//1 is >=cut
if(pref == ops) {//last is P
cut = pref;
} else {
cut = n - suf + 1;
}
vector<int> segs;
int last = -1;
for(auto i : mid_p) {
i = i >= cut;
if(last != i) segs.push_back(1);
else segs.back()++;
last = i;
}
if(segs.size() < 3) return 1;
segs.resize(4);
for(int op = mid_op + 1; op <= ops; op++) {
if(op % 2 == 1) {//prefix
while(segs[0] + segs[1] < op && segs[2])
segs[2]--, segs[0]++;
} else {//suffix
while(segs[3] + segs[2] < op && segs[1])
segs[1]--, segs[3]++;
}
}
return (segs[0] == 0 || segs[2] == 0) && (segs[1] == 0 || segs[3] == 0);
};
int ans = -1;
for(int z = 1<<20; z>>=1;)
ans += z*!check(ans+z);
return ans + 1;
}
int main() {
cin.tie(0)->sync_with_stdio(0);
int n;
cin >> n;
vector<int> p(n);
for(auto &i : p) cin >> i, i--;
int cnt1 = solve(p);
reverse(all(p));
for(auto &i : p) i = n-1-i;
int cnt2 = solve(p);
string pat = "PS";
if(cnt2 < cnt1) cnt1 = cnt2, pat = "SP";
for(int i = 0; i < cnt1; i++) cout << pat[i&1];cout << ".\n";
}
Details
Tip: Click on the bar to expand more detailed information
Test #1:
score: 100
Accepted
time: 1ms
memory: 3552kb
input:
3 1 2 3
output:
.
result:
ok OK 0 operations
Test #2:
score: 0
Accepted
time: 1ms
memory: 3528kb
input:
2 2 1
output:
PS.
result:
ok OK 2 operations
Test #3:
score: 0
Accepted
time: 1ms
memory: 3628kb
input:
9 3 2 4 1 5 6 7 9 8
output:
SPSP.
result:
ok OK 4 operations
Test #4:
score: 0
Accepted
time: 1ms
memory: 3544kb
input:
10 2 9 5 7 10 6 3 1 8 4
output:
PSPSPSPS.
result:
ok OK 8 operations
Test #5:
score: -100
Wrong Answer
time: 1ms
memory: 3604kb
input:
13 9 8 5 4 3 2 1 13 12 11 10 7 6
output:
PSPSPSPSP.
result:
wrong answer Jury (8) found answer better than participant (9)