AtCoder Beginner Contest 169
BC是一些常见的技巧，D题很水，E比较有意思，考虑成为中位数的充要条件即可，主要是注意到某些不与相交的区间个数。F的话是一个不是很难的dp，把计算过程分散到dp过程即可。具体的话可以看看视频题解。
以下是代码：
A - Multiplication 1
/*
* Author: heyuhhh
* Created Time: 2020/5/31 20:00:31
*/
#include <iostream>
#include <algorithm>
#include <cstring>
#include <cstdio>
#include <vector>
#include <cmath>
#include <set>
#include <map>
#include <queue>
#include <iomanip>
#include <assert.h>
#include <functional>
#include <numeric>
#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; cin >> a >> b;
cout << a * b << '\n';
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
cout << fixed << setprecision(20);
run();
return 0;
}
B - Multiplication 2
/*
* Author: heyuhhh
* Created Time: 2020/5/31 20:01:06
*/
#include <iostream>
#include <algorithm>
#include <cstring>
#include <cstdio>
#include <vector>
#include <cmath>
#include <set>
#include <map>
#include <queue>
#include <iomanip>
#include <assert.h>
#include <functional>
#include <numeric>
#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;
const ll MAX = 1e18;
void run() {
int n; cin >> n;
vector <ll> a(n);
for (int i = 0; i < n; i++) {
cin >> a[i];
}
for (int i = 0; i < n; i++) if (a[i] == 0) {
cout << 0 << '\n';
return;
}
ll ans = 1;
for (int i = 0; i < n; i++) {
if (a[i] > MAX / ans) {
cout << -1 << '\n';
return;
}
ans *= a[i];
}
cout << ans << '\n';
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
cout << fixed << setprecision(20);
run();
return 0;
}
C - Multiplication 3
/*
* Author: heyuhhh
* Created Time: 2020/5/31 20:11:10
*/
#include <iostream>
#include <algorithm>
#include <cstring>
#include <cstdio>
#include <vector>
#include <cmath>
#include <set>
#include <map>
#include <queue>
#include <iomanip>
#include <assert.h>
#include <functional>
#include <numeric>
#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;
const double eps = 1e-7;
void run() {
ll A;
double B;
cin >> A >> B;
ll C = ll(B * 100 + 0.5);
ll ans = A * C;
cout << ll(ans / 100) << '\n';
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
cout << fixed << setprecision(20);
run();
return 0;
}
D - Div Game
/*
* Author: heyuhhh
* Created Time: 2020/5/31 20:16:37
*/
#include <iostream>
#include <algorithm>
#include <cstring>
#include <cstdio>
#include <vector>
#include <cmath>
#include <set>
#include <map>
#include <queue>
#include <iomanip>
#include <assert.h>
#include <functional>
#include <numeric>
#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() {
ll n; cin >> n;
int ans = 0;
for (int i = 2; 1ll * i * i <= n; i++) {
if (n % i == 0) {
int cnt = 0;
int tot = 1;
while (n % i == 0) {
n /= i;
++cnt;
if (cnt == tot) {
cnt = 0;
++ans;
++tot;
}
}
}
}
if (n > 1) ++ans;
cout << ans << '\n';
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
cout << fixed << setprecision(20);
run();
return 0;
}
E - Count Median
/*
* Author: heyuhhh
* Created Time: 2020/5/31 20:46:05
*/
#include <iostream>
#include <algorithm>
#include <cstring>
#include <cstdio>
#include <vector>
#include <cmath>
#include <set>
#include <map>
#include <queue>
#include <iomanip>
#include <assert.h>
#include <functional>
#include <numeric>
#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;
struct seg {
int l, r;
}a[N];
int n;
int findL(int k) {
return a[k + 1].r;
}
int findR(int k) {
return a[k + 1].l;
}
seg find(int k) {
sort(a + 1, a + n + 1, [&](seg A, seg B) {
return A.r < B.r;
});
int r = findL(k - 1);
sort(a + 1, a + n + 1, [&](seg A, seg B) {
return A.l > B.l;
});
int l = findR(n - k);
return seg{l, r};
}
void run() {
cin >> n;
for (int i = 1; i <= n; i++) {
int l, r; cin >> l >> r;
a[i] = seg{l, r};
}
if (n & 1) {
seg res = find(n / 2 + 1);
int ans = max(0, res.r - res.l + 1);
cout << ans << '\n';
} else {
seg res1 = find(n / 2), res2 = find(n / 2 + 1);
int Min = res1.l + res2.l, Max = res1.r + res2.r;
int ans = max(0, Max - Min + 1);
cout << ans << '\n';
}
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
cout << fixed << setprecision(20);
run();
return 0;
}
F - Knapsack for All Subsets
/*
* Author: heyuhhh
* Created Time: 2020/5/31 21:11:22
*/
#include <iostream>
#include <algorithm>
#include <cstring>
#include <cstdio>
#include <vector>
#include <cmath>
#include <set>
#include <map>
#include <queue>
#include <iomanip>
#include <assert.h>
#include <functional>
#include <numeric>
#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 = 3000 + 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 n, s;
int a[N];
int dp[N][N];
void add(int& x, int y) {
x += y;
if (x >= MOD) x -= MOD;
}
void run() {
cin >> n >> s;
for (int i = 1; i <= n; i++) {
cin >> a[i];
}
dp[0][0] = qpow(2, n);
int inv2 = (MOD + 1) / 2;
for (int i = 1; i <= n; i++) {
for (int j = 0; j <= s; j++) {
if (j >= a[i]) {
dp[i][j] = 1ll * dp[i - 1][j - a[i]] * inv2 % MOD;
}
dp[i][j] = (dp[i][j] + dp[i - 1][j]) % MOD;
}
}
cout << dp[n][s] << '\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。
