Educational Codeforces Round 21
Educational Codeforces Round 21
https://codeforces.com/contest/808
苯比只会ABC，呜呜，
A. Lucky Year
被pow()坑了
#include <bits/stdc++.h>
#define ll long long
using namespace std;
ll pw[] = {1, 10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000, 1000000000};
int main () {
ll n;
cin >> n;
string s = to_string (n);
//cout << s << endl;
int x = s[0] - '0' + 1;
cout << (ll)(x * pw[s.size () - 1] - n);
}
//len: 1-9
B. Average Sleep Time
如题
#include <bits/stdc++.h>
#define ll long long
using namespace std;
const int N = 2e5 + 5;
ll a[N];
int main () {
int n, k;
cin >> n >> k;
ll sum = 0;
for (int i = 1; i <= n; i++) cin >> a[i], a[i] += a[i-1];
for (int i = k; i <= n; i++) sum += a[i] - a[i - k];
cout << fixed << setprecision (9) << 1.0 * (sum) / (n - k + 1);
}
C. Tea Party
细节模拟
#include <bits/stdc++.h>
#define ll long long
using namespace std;
typedef pair<int, int> pii;
const int N = 2e5 + 5;
ll a[N], n, sum, maxsum, base;
int ans[N];
pii v[N];
int main () {
cin >> n >> sum;
for (int i = 1; i <= n; i++) {
int x;
cin >> x;
v[i] = {x, i};
base += (x + 1) / 2;
maxsum += x;
}
if (sum < base || maxsum < sum) {
cout << -1 << endl;
return 0;
}
sum -= base;
sort (v + 1, v + n + 1, greater <pii>());
//前面贪心塞满
//cout << sum << endl;
for (int i = 1; i <= n; i++) {
if (sum <= 0) {
for (int j = i; j <= n; j++) ans[v[j].second] = (v[j].first + 1) / 2;
break;
}
int x = v[i].first, id = v[i].second;
//cout << x << ' ' << id << ' ';
ans[id] = (x + 1) / 2;
if (sum >= x / 2) ans[id] = x, sum -= (x / 2); //装满
else ans[id] += sum, sum = 0;
//cout << sum << endl;
}
for (int i = 1; i <= n; i++) cout << ans[i] << ' ';
}
D. Array Division
没审清楚题目！！只能移动一次，直接map就好，要注意若干个爆int的地方
#include <bits/stdc++.h>
#define ll long long
using namespace std;
const int N = 100005;
ll a[N], n;
ll sum, cur;
int main () {
int n;
cin >> n;
map<ll, int> pre, suf; //记录出现的数
for (int i = 1; i <= n; i++) {
cin >> a[i];
sum += a[i];
suf[a[i]] ++;
}
if (sum & 1) {
cout << "NO";
return 0;
}
sum /= 2;
for (int i = 1; i <= n; i++) {
cur += a[i];
if (cur == sum) {
cout << "YES\n";
return 0;
}
pre[a[i]] ++, suf[a[i]] --;
ll dx = abs (cur - sum);
if ((cur > sum && pre[dx]) || (cur < sum && suf[dx])) {
cout << "YES\n";
return 0;
}
}
cout << "NO\n";
}
//能否分成两段相等的和
//sum已知
//只能移动一次!!!
