로프
18 August 2019
문제 : https://www.acmicpc.net/problem/2217
이번은 그리디하게 최적값을 찾아내는 문제를 풀어보도록 하겠습니다.
#include<stdio.h>
void mergeSort(int arr[], int low, int high);
int main(void) {
int N;
scanf("%d", &N);
int* arr = new int[N];
for (int i = 0; i < N; i++)
{
scanf("%d", &arr[i]);
}
mergeSort(arr, 0, N - 1);
int max = 0;
int count = 1;
for (int i = N - 1; i >= 0; i--)
{
if (count * arr[i] > max)
{
max = count * arr[i];
}
count++;
}
printf("%d", max);
return 0;
}
void merge(int arr[], int l, int m, int r)
{
int i, j, k;
int n1 = m - l + 1;
int n2 = r - m;
int* L = new int[n1];
int* R = new int[n2];
for (i = 0; i < n1; i++)
L[i] = arr[l + i];
for (j = 0; j < n2; j++)
R[j] = arr[m + 1 + j];
i = 0;
j = 0;
k = l;
while (i < n1 && j < n2)
{
if (L[i] <= R[j])
{
arr[k] = L[i];
i++;
}
else
{
arr[k] = R[j];
j++;
}
k++;
}
while (i < n1)
{
arr[k] = L[i];
i++;
k++;
}
while (j < n2)
{
arr[k] = R[j];
j++;
k++;
}
}
void mergeSort(int arr[], int l, int r)
{
if (l < r)
{
int m = l + (r - l) / 2;
mergeSort(arr, l, m);
mergeSort(arr, m + 1, r);
merge(arr, l, m, r);
}
}