Educational Codeforces Round 9
Educational Codeforces Round 9
https://codeforces.com/contest/632
3/6: ABC
A. Grandma Laura and Apples
模拟
#include <bits/stdc++.h>
#define int long long
using namespace std;
const int N = 45;
int n, m, a[N], ans, money;
signed main () {
cin >> n >> m;
string s;
m /= 2;
for (int i = 0; i < n; i++) {
cin >> s;
if (s.size () == 8) a[i] = 1;
}
for (int i = n - 1; i >= 0; i--) {
money *= 2;
if (a[i]) money ++;
ans += money;
}
cout << m * ans;
}
//x = 2^{n-1} + 2^{cnt-1} - 1
//
B. Alice, Bob, Two Teams
前缀和
#include <bits/stdc++.h>
#define int long long
using namespace std;
const int N = 5e5 + 5;
int n, a[N], ans;
int preA[N], preB[N], sufA[N], sufB[N];
signed main () {
string s;
cin >> n;
for (int i = 1; i <= n; i++) cin >> a[i];
cin >> s;
s = ' ' + s;
for (int i = 1; i <= n; i++) {
preA[i] = preA[i-1], preB[i] = preB[i-1];
if (s[i] == 'A') preA[i] += a[i];
else preB[i] += a[i], ans += a[i];
}
for (int i = n; i >= 1; i--) {
sufA[i] = sufA[i+1], sufB[i] = sufB[i+1];
if (s[i] == 'A') sufA[i] += a[i];
else sufB[i] += a[i];
}
for (int i = 1; i <= n; i++) {
//假设在i翻转前缀
ans = max (ans, preA[i] + sufB[i+1]);
}
for (int i = n; i >= 1; i--) {
//假设在i翻转后缀
ans = max (ans, sufA[i] + preB[i-1]);
}
cout << ans;
}
C. The Smallest String Concatenation
排序水题
#include <bits/stdc++.h>
using namespace std;
const int N = 5e4 + 5;
int n;
string s[N];
bool cmp (string a, string b) {
return a + b < b + a;
}
int main () {
cin >> n;
for (int i = 0; i < n; i++) cin >> s[i];
sort (s, s + n, cmp);
for (int i = 0; i < n; i++) cout << s[i];
}
D. Longest Subsequence
离散化 + 筛因数
这题其实非常简单，但是当时没思考qaq
// LUOGU_RID: 98487907
#include <bits/stdc++.h>
#define int long long
using namespace std;
const int N = 1e6 + 5;
int n, m, a[N], cnt[N], b[N], ans[N];
int lcm = 1, tot, k;
signed main () {
cin >> n >> m;
for (int i = 1; i <= n; i++) {
cin >> a[i];
if (a[i] > m) continue;
b[k++] = a[i], cnt[a[i]] ++;
}
sort (b, b + k);
k = unique (b, b + k) - b;
for (int i = 0; i < k; i++) {
for (int j = b[i]; j <= m; j += b[i]) ans[j] += cnt[b[i]];
}
for (int i = 1; i <= m; i++) {
if (ans[i] > tot) tot = ans[i], lcm = i;
}
cout << lcm << ' ' << tot << endl;
for (int i = 1; i <= n; i++) {
if (lcm % a[i] == 0) cout << i << ' ';
}
}
剩下眼睛不舒服，明天补
