C - Final Day Editorial by en_translator
It is possible that the \(i\)-th student is ranked in the top \(K\) if and only if, should he/she get \(300\) points while the other students get \(0\) points on the \(4\)-th day, he/she would rank in the top \(K\).
Let \(S_i\) be the sum of \(i\)-th student’s score for the first three days.
Also, let \(T\) be the \(K\)-th largest value among \(S_1, \dots, S_N\). If \(S_i + 300 \geq T\) then the answer is \(S_i + 300 \geq T\); otherwise the answer is No
.
Sample code (C++):
#include <bits/stdc++.h>
using namespace std;
int main() {
int n, k;
cin >> n >> k;
k -= 1;
vector<int> p(n);
for (int& x : p) {
int a, b, c;
cin >> a >> b >> c;
x = a + b + c;
}
vector<int> q = p;
sort(begin(q), end(q), greater<>());
for (int x : p) {
cout << (x + 300 >= q[k] ? "Yes" : "No") << '\n';
}
}
Sample code (Python) :
n, k = map(int, input().split())
s = [0] * n;
for i in range(n):
s[i] = sum(map(int, input().split()))
t = sorted(s, reverse=True)[k - 1];
for x in s:
print("Yes" if x + 300 >= t else "No")
In the codes above, the array is sorted in order to find the \(K\)-th largest value, so the worst complexity is \(\Theta (N \log N)\). However, one can use selection algorithm to reduce computational complexity to \(O(N)\).
In C++, std::nth_element
is available:
#include <bits/stdc++.h>
using namespace std;
int main() {
int n, k;
cin >> n >> k;
k -= 1;
vector<int> p(n);
for (int& x : p) {
int a, b, c;
cin >> a >> b >> c;
x = a + b + c;
}
vector<int> q = p;
nth_element(begin(q), begin(q) + k, end(q), greater<>());
for (int x : p) {
cout << (x + 300 >= q[k] ? "Yes" : "No") << '\n';
}
}
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