cp/usaco/bronze/complete-search/tracing.cc
2025-04-30 16:28:40 -04:00

168 lines
4 KiB
C++

#include <bits/stdc++.h> // {{{
// https://codeforces.com/blog/entry/96344
#pragma GCC optimize("O2,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
using namespace std;
using i32 = int32_t;
using u32 = uint32_t;
using i64 = int64_t;
using u64 = uint64_t;
using f64 = double;
using f128 = long double;
#if __cplusplus >= 202002L
template <typename T> constexpr T MIN = std::numeric_limits<T>::min();
template <typename T> constexpr T MAX = std::numeric_limits<T>::max();
template <typename T> [[nodiscard]] static T sc(auto &&x) {
return static_cast<T>(x);
}
template <typename T> [[nodiscard]] static T sz(auto &&x) {
return static_cast<T>(x.size());
}
#endif
static void NO() { std::cout << "NO\n"; }
static void YES() { std::cout << "YES\n"; }
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define ff first
#define ss second
#ifdef LOCAL
#define db(...) std::print(__VA_ARGS__)
#define dbln(...) std::println(__VA_ARGS__)
#else
#define db(...)
#define dbln(...)
#endif
// }}}
vector<pair<i32, i32>> trace(251);
void solve() {
/*
- # cows patient 0
- k bounds
1. sort by time to "sim" interactions
- say x and y shake; unless wek one is sick, wedk consequences
(i.e. who gets sick)
- only ONE starts out
- guess ONE cow is patient zero, run sim
- guess all k from 0 to 251?, taking min of low bound, max of high bound
k = 250 -> infinity
bsearch <- no (if can achieve state w/ k=i, doesn't mean k=i-1, nor k=i+1)
NOTE: only candidates for patient zero are initial set 0s, since cows stay sick
*/
u32 n, t;
cin >> n >> t;
string state;
cin >> state;
state = '0' + state;
u32 t_;
for (u32 i = 0; i < t; ++i) {
cin >> t_;
cin >> trace[t_].ff >> trace[t_].ss;
// NOTE: forgot the one-indexin
}
u32 lb = numeric_limits<u32>::max(), ub = 0;
u32 count = 0;
/*
a bunch of cows shake hooves because the gay USACO (usa computing olympiad)
just decided to theme everything cows
and for some K, a cow can only transmit what you have (STDs)
after at most K hooveshakes
but i misread it as saying that if they contract what you have (an STD)
they can only transmit the STD up to K days later
not after they have sex k times (which is what you do, let k approach
infinity)
ok. then, after that, i missed k=0 basecase
then, after that
basically, i only counted when someone transmitted an std & infecting someone
instead, i should've counted the cow having sex with ANYONE, even if they already
have an std, it still counts as a handshake
core note: once realize wrong, reexamine entire problem solution (has rpercussions) rather than what u see is wrong
*/
for (u32 i = 1; i <= n; ++i) {
bool zero = false;
for (u32 k = 0; k <= 250; ++k) {
vector<u32> shakes(n + 1, 0);
string cur_state(n + 1, '0');
cur_state[i] = '1';
for (t_ = 1; t_ <= 250; ++t_) {
auto [a, b] = trace[t_];
if (a == 0) {
continue;
}
if (cur_state[a] == '1') {
++shakes[a];
}
if (cur_state[b] == '1') {
++shakes[b];
}
if (cur_state[a] == '0' && cur_state[b] == '1' && shakes[b] <= k) {
cur_state[a] = '1';
} else if (cur_state[b] == '0' && cur_state[a] == '1' &&
shakes[a] <= k) {
cur_state[b] = '1';
}
}
if (cur_state == state) {
zero = true;
lb = min(lb, k);
ub = max(ub, k);
}
}
count += zero;
}
cout << count << ' ' << lb << ' ' << (ub == 250 ? "Infinity" : to_string(ub))
<< '\n';
}
int main() { // {{{
cin.tie(nullptr)->sync_with_stdio(false);
cin.exceptions(cin.failbit);
#define PROBLEM_NAME "tracing"
#ifdef LOCAL
freopen("io/" PROBLEM_NAME ".in", "r", stdin);
freopen("io/" PROBLEM_NAME ".out", "w", stdout);
#else
freopen(PROBLEM_NAME ".in", "r", stdin);
freopen(PROBLEM_NAME ".out", "w", stdout);
#endif
solve();
return 0;
}
// }}}