给定一个长度为N的数组arr[] ,任务是选择一个四元组(i, j, k, l)并计算所有可能的四元组的第二个最小值的总和。
注意:保证N是4的倍数,并且每个数组元素都可以是单个四元组的一部分。
例子:
Input: arr[] = {7, 4, 5, 2, 3, 1, 5, 9}
Output: 8
Explanation:
Quadruple 1: {7, 1, 5, 9} => 2nd Minimum value = 5.
Quadruple 2: {4, 5, 2, 3} => 2nd Minimum value = 3.
Therefore, the maximum possible sum is 8.
Input: arr[] = {7, 4, 3, 3}
Output: 3
方法:想法是使用Greedy Approach来解决这个问题。以下是步骤:
- 初始化一个变量,比如sum ,以存储数组中的最大增益。
- 按升序对数组进行排序。
- 反向遍历数组并添加遇到的每三个元素。
- 打印获得的总和。
下面是上述方法的实现:
C++
// C++ program for the above approach
#include
#include
using namespace std;
// Function to find maximum possible sum of
// second minimums in each quadruple
void maxPossibleSum(int arr[], int N)
{
// Sort the array
sort(arr, arr + N);
int sum = 0;
int j = N - 3;
while (j >= 0)
{
// Add the second minimum
sum += arr[j];
j -= 3;
}
// Print maximum possible sum
cout << sum;
}
// Driver Code
int main()
{
// Given array
int arr[] = { 7, 4, 5, 2, 3, 1, 5, 9 };
// Size of the array
int N = 8;
maxPossibleSum(arr, N);
return 0;
}
// This code is contributed by aditya7409
Java
// Java program for the above approach
import java.io.*;
import java.util.*;
class GFG {
// Function to find maximum possible sum of
// second minimums in each quadruple
public static void maxPossibleSum(int[] arr, int N)
{
// Sort the array
Arrays.sort(arr);
int sum = 0;
int j = N - 3;
while (j >= 0) {
// Add the second minimum
sum += arr[j];
j -= 3;
}
// Print maximum possible sum
System.out.println(sum);
}
// Driver Code
public static void main(String[] args)
{
// Given array
int[] arr = { 7, 4, 5, 2, 3, 1, 5, 9 };
// Size of the array
int N = arr.length;
maxPossibleSum(arr, N);
}
}
Python3
# Python 3 program for the above approach
# Function to find maximum possible sum of
# second minimums in each quadruple
def maxPossibleSum(arr, N):
# Sort the array
arr.sort()
sum = 0
j = N - 3
while (j >= 0):
# Add the second minimum
sum += arr[j]
j -= 3
# Print maximum possible sum
print(sum)
# Driver Code
if __name__ == "__main__":
# Given array
arr = [7, 4, 5, 2, 3, 1, 5, 9]
# Size of the array
N = 8
maxPossibleSum(arr, N)
# This code is contributed by chitranayal
C#
// C# program for the above approach
using System;
public class GFG
{
// Function to find maximum possible sum of
// second minimums in each quadruple
public static void maxPossibleSum(int[] arr, int N)
{
// Sort the array
Array.Sort(arr);
int sum = 0;
int j = N - 3;
while (j >= 0)
{
// Add the second minimum
sum += arr[j];
j -= 3;
}
// Print maximum possible sum
Console.WriteLine(sum);
}
// Driver Code
public static void Main(String[] args)
{
// Given array
int[] arr = { 7, 4, 5, 2, 3, 1, 5, 9 };
// Size of the array
int N = arr.Length;
maxPossibleSum(arr, N);
}
}
// This code is contributed by shikhasingrajput
Javascript
输出:
8
时间复杂度: O(N)
辅助空间: O(1)
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