AtCoder Beginner Contest 167
还是视频题解，但感觉有点没说清楚的地方。。
\(F\)感觉有点没有讲清楚，最后\(b_i<0\)的情况，我们按照\(a_i+b_j<a_j+b_i\)进行排序。考虑对\(i,j\)两个位置安排顺序，并且考虑先放\(i\)再放\(j\)，先放\(j\)再放\(i\)两种情况，我们假设两个首先都能成功放上，那么就需要使得\(a_i+b_j\)尽可能大，此时后面就越有可能放上去。
如果第一个不能放上呢，那么之后的顺序无论怎样，都是不合法的，最后就类似于这样的：11110000，1表示合法，0表示不合法，我们前面已经放上了一些，从第一个0开始，我们顺序其实已经无所谓了。所以我们不用考虑不能放上的情况。
那么把能放上的情况考虑就行。
代码如下：
A - Registration
/*
* Author: heyuhhh
* Created Time: 2020/5/10 20:00:37
*/
#include <iostream>
#include <algorithm>
#include <cstring>
#include <cstdio>
#include <vector>
#include <cmath>
#include <set>
#include <map>
#include <queue>
#include <iomanip>
#include <assert.h>
#define MP make_pair
#define fi first
#define se second
#define pb push_back
#define sz(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()
#define INF 0x3f3f3f3f
#define Local
#ifdef Local
#define dbg(args...) do { cout << #args << " -> "; err(args); } while (0)
void err() { std::cout << std::endl; }
template<typename T, typename...Args>
void err(T a, Args...args) { std::cout << a << ' '; err(args...); }
template <template<typename...> class T, typename t, typename... A>
void err(const T <t> &arg, const A&... args) {
for (auto &v : arg) std::cout << v << ' '; err(args...); }
#else
#define dbg(...)
#endif
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
//head
const int N = 1e5 + 5;
void run() {
string s, t; cin >> s >> t;
int n = s.length(), m = t.length();
if (m == n + 1 && t.substr(0, n) == s) {
cout << "Yes" << '\n';
} else cout << "No" << '\n';
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
cout << fixed << setprecision(20);
run();
return 0;
}
B - Easy Linear Programming /
/*
* Author: heyuhhh
* Created Time: 2020/5/10 20:03:01
*/
#include <iostream>
#include <algorithm>
#include <cstring>
#include <cstdio>
#include <vector>
#include <cmath>
#include <set>
#include <map>
#include <queue>
#include <iomanip>
#include <assert.h>
#define MP make_pair
#define fi first
#define se second
#define pb push_back
#define sz(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()
#define INF 0x3f3f3f3f
#define Local
#ifdef Local
#define dbg(args...) do { cout << #args << " -> "; err(args); } while (0)
void err() { std::cout << std::endl; }
template<typename T, typename...Args>
void err(T a, Args...args) { std::cout << a << ' '; err(args...); }
template <template<typename...> class T, typename t, typename... A>
void err(const T <t> &arg, const A&... args) {
for (auto &v : arg) std::cout << v << ' '; err(args...); }
#else
#define dbg(...)
#endif
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
//head
const int N = 1e5 + 5;
void run() {
int A, B, C, k; cin >> A >> B >> C >> k;
int ans = min(A, k);
k -= ans;
if (k) {
k -= B;
}
if (k > 0) {
ans -= min(C, k);
}
cout << ans << '\n';
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
cout << fixed << setprecision(20);
run();
return 0;
}
C - Skill Up
/*
* Author: heyuhhh
* Created Time: 2020/5/10 20:06:28
*/
#include <iostream>
#include <algorithm>
#include <cstring>
#include <cstdio>
#include <vector>
#include <cmath>
#include <set>
#include <map>
#include <queue>
#include <iomanip>
#include <assert.h>
#define MP make_pair
#define fi first
#define se second
#define pb push_back
#define sz(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()
#define INF 0x3f3f3f3f
#define Local
#ifdef Local
#define dbg(args...) do { cout << #args << " -> "; err(args); } while (0)
void err() { std::cout << std::endl; }
template<typename T, typename...Args>
void err(T a, Args...args) { std::cout << a << ' '; err(args...); }
template <template<typename...> class T, typename t, typename... A>
void err(const T <t> &arg, const A&... args) {
for (auto &v : arg) std::cout << v << ' '; err(args...); }
#else
#define dbg(...)
#endif
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
//head
const int N = 1e5 + 5;
void run() {
int n, m, x; cin >> n >> m >> x;
vector <vector <int>> a(n);
for (int i = 0; i < n; i++) {
int k; cin >> k;
a[i].resize(m + 1);
a[i][m] = k;
for (int j = 0; j < m; j++) {
cin >> a[i][j];
}
}
int ans = INF;
for (int i = 0; i < 1 << n; i++) {
vector <int> cnt(m, 0);
int res = 0;
for (int j = 0; j < n; j++) if (i >> j & 1) {
res += a[j][m];
for (int k = 0; k < m; k++) {
cnt[k] += a[j][k];
}
}
bool f = true;
for (auto it : cnt) {
if (it < x) f = false;
}
if (f) {
ans = min(ans, res);
}
}
if (ans == INF) ans = -1;
cout << ans << '\n';
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
cout << fixed << setprecision(20);
run();
return 0;
}
D - Teleporter
/*
* Author: heyuhhh
* Created Time: 2020/5/10 20:13:08
*/
#include <iostream>
#include <algorithm>
#include <cstring>
#include <cstdio>
#include <vector>
#include <cmath>
#include <set>
#include <map>
#include <queue>
#include <iomanip>
#include <assert.h>
#define MP make_pair
#define fi first
#define se second
#define pb push_back
#define sz(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()
#define INF 0x3f3f3f3f
#define Local
#ifdef Local
#define dbg(args...) do { cout << #args << " -> "; err(args); } while (0)
void err() { std::cout << std::endl; }
template<typename T, typename...Args>
void err(T a, Args...args) { std::cout << a << ' '; err(args...); }
template <template<typename...> class T, typename t, typename... A>
void err(const T <t> &arg, const A&... args) {
for (auto &v : arg) std::cout << v << ' '; err(args...); }
#else
#define dbg(...)
#endif
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
//head
void run() {
int n; ll k;
cin >> n >> k;
vector <int> a(n);
for (int i = 0; i < n; i++) {
cin >> a[i]; --a[i];
}
vector <int> vis(n);
vector <int> sta, cyc;
int x = 0;
while (1) {
vis[x] = 1;
sta.push_back(x);
x = a[x];
if (vis[x]) {
while (1) {
cyc.push_back(sta.back());
int t = sta.back();
sta.pop_back();
if (t == x) {
break;
}
}
break;
}
}
reverse(all(cyc));
if (k < sz(sta)) {
cout << sta[k] + 1 << '\n';
} else {
k -= sz(sta);
k %= sz(cyc);
cout << cyc[k] + 1 << '\n';
}
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
cout << fixed << setprecision(20);
run();
return 0;
}
E - Colorful Blocks
/*
* Author: heyuhhh
* Created Time: 2020/5/10 20:57:40
*/
#include <iostream>
#include <algorithm>
#include <cstring>
#include <cstdio>
#include <vector>
#include <cmath>
#include <set>
#include <map>
#include <queue>
#include <iomanip>
#include <assert.h>
#define MP make_pair
#define fi first
#define se second
#define pb push_back
#define sz(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()
#define INF 0x3f3f3f3f
#define Local
#ifdef Local
#define dbg(args...) do { cout << #args << " -> "; err(args); } while (0)
void err() { std::cout << std::endl; }
template<typename T, typename...Args>
void err(T a, Args...args) { std::cout << a << ' '; err(args...); }
template <template<typename...> class T, typename t, typename... A>
void err(const T <t> &arg, const A&... args) {
for (auto &v : arg) std::cout << v << ' '; err(args...); }
#else
#define dbg(...)
#endif
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
//head
const int N = 2e5 + 5, MOD = 998244353;
int qpow(ll a, ll b) {
ll res = 1;
while (b) {
if (b & 1) res = res * a % MOD;
a = a * a % MOD;
b >>= 1;
}
return res;
}
int fac[N], inv[N];
void run() {
int n, m, k;
cin >> n >> m >> k;
fac[0] = 1;
for (int i = 1; i <= n; i++) fac[i] = 1ll * fac[i - 1] * i % MOD;
inv[n] = qpow(fac[n], MOD - 2);
for (int i = n - 1; i >= 0; i--) inv[i] = 1ll * inv[i + 1] * (i + 1) % MOD;
int ans = 0;
for (int t = n - k; t <= n; t++) {
//x_1+x_2+..x_t = n
int res = 1ll * m * qpow(m - 1, t - 1) % MOD;
res = 1ll * res * fac[n - 1] % MOD * inv[t - 1] % MOD * inv[n - t] % MOD;
ans = (ans + res) % MOD;
}
cout << ans << '\n';
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
cout << fixed << setprecision(20);
run();
return 0;
}
F - Bracket Sequencing
/*
* Author: heyuhhh
* Created Time: 2020/5/10 21:13:22
*/
#include <iostream>
#include <algorithm>
#include <cstring>
#include <cstdio>
#include <vector>
#include <cmath>
#include <set>
#include <map>
#include <queue>
#include <iomanip>
#include <assert.h>
#define MP make_pair
#define fi first
#define se second
#define pb push_back
#define sz(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()
#define INF 0x3f3f3f3f
#define Local
#ifdef Local
#define dbg(args...) do { cout << #args << " -> "; err(args); } while (0)
void err() { std::cout << std::endl; }
template<typename T, typename...Args>
void err(T a, Args...args) { std::cout << a << ' '; err(args...); }
template <template<typename...> class T, typename t, typename... A>
void err(const T <t> &arg, const A&... args) {
for (auto &v : arg) std::cout << v << ' '; err(args...); }
#else
#define dbg(...)
#endif
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
//head
const int N = 1e6 + 5;
void run() {
int n; cin >> n;
vector <pii> z(n), f(n), o(n);
for (int i = 1; i <= n; i++) {
string s; cin >> s;
int k = s.length();
int x = 0, Min = INF;
for (int j = 0; j < k; j++) {
if (s[j] == '(') ++x;
else --x;
Min = min(Min, x);
}
if (x > 0) z.push_back(MP(Min, x));
else if (x == 0) o.push_back(MP(Min, x));
else f.push_back(MP(Min, x));
}
sort(all(z), [&] (pii A, pii B) {
return A.fi > B.fi;
});
sort(all(f), [&] (pii A, pii B) {
return A.se + B.fi > A.fi + B.se;
});
int tot = 0;
for (int i = 0; i < sz(z); i++) {
pii now = z[i];
if (tot + now.fi >= 0) {
tot += now.se;
} else {
cout << "No" << '\n';
return;
}
}
for (int i = 0; i < sz(o); i++) {
pii now = o[i];
if (tot + now.fi < 0) {
cout << "No" << '\n';
return;
}
}
for (int i = 0; i < sz(f); i++) {
pii now = f[i];
if (tot + now.fi >= 0) {
tot += now.se;
} else {
cout << "No" << '\n';
return;
}
}
if (tot != 0) cout << "No" << '\n';
else cout << "Yes" << '\n';
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
cout << fixed << setprecision(20);
run();
return 0;
}
重要的是自信，一旦有了自信，人就会赢得一切。
