最长子序列总和最大

给定大小为N的数组arr [] ，任务是从给定数组中求和之和最大的最长非空子序列。

例子：

Input: arr[] = { 1, 2, -4, -2, 3, 0 } 
Output: 1 2 3 0 
Explanation: 
Sum of elements of the subsequence {1, 2, 3, 0} is 6 which is the maximum possible sum. 
Therefore, the required output is 1 2 3 0

Input: arr[] = { -10, -6, -2, -3, -4 } 
Output: -2

天真的方法：解决此问题的最简单方法是遍历数组并生成给定数组的所有可能子序列，然后计算它们的总和。以最大总和打印所有子序列中最长的子序列。

时间复杂度： O(N * 2 ^N )
辅助空间： O(N)

高效的方法：可以使用贪婪技术解决问题。请按照以下步骤解决问题：

• 初始化一个变量，例如maxm ，以存储给定数组的最大元素。
• 如果maxm <0 ，则打印maxm的值。
• 否则，遍历数组并打印所有正数组元素。

下面是上述方法的实现：

C++

// C++ program to implement
// the above approach
 
#include 
using namespace std;
 
// Function to find the longest subsequence
// from the given array with maximum sum
void longestSubWithMaxSum(int arr[], int N)
{
    // Stores the largest element
    // of the array
    int Max = *max_element(arr,
                           arr + N);
 
    // If Max is less than 0
    if (Max < 0) {
 
        // Print the largest element
        // of the array
        cout << Max;
        return;
    }
 
    // Traverse the array
    for (int i = 0; i < N; i++) {
 
        // If arr[i] is greater
        // than or equal to 0
        if (arr[i] >= 0) {
 
            // Print elements of
            // the subsequence
            cout << arr[i] << " ";
        }
    }
}
 
// Driver Code
int main()
{
    int arr[] = { 1, 2, -4, -2, 3, 0 };
 
    int N = sizeof(arr) / sizeof(arr[0]);
 
    longestSubWithMaxSum(arr, N);
    return 0;
}

Java

// Java program to implement
// the above approach
import java.util.*;
  
class GFG{
  
// Function to find the longest subsequence
// from the given array with maximum sum
static void longestSubWithMaxSum(int arr[], int N)
{
     
    // Stores the largest element
    // of the array
    int Max = Arrays.stream(arr).max().getAsInt();
  
    // If Max is less than 0
    if (Max < 0)
    {
         
        // Print the largest element
        // of the array
        System.out.print(Max);
        return;
    }
  
    // Traverse the array
    for(int i = 0; i < N; i++)
    {
         
        // If arr[i] is greater
        // than or equal to 0
        if (arr[i] >= 0)
        {
             
            // Print elements of
            // the subsequence
            System.out.print(arr[i] + " ");
        }
    }
}
  
// Driver Code
public static void main(String[] args)
{
    int arr[] = { 1, 2, -4, -2, 3, 0 };
    int N = arr.length;
  
    longestSubWithMaxSum(arr, N);
}
}
 
// This code is contributed by code_hunt

Python3

# Python3 program to implement
# the above approach
 
# Function to find the longest subsequence
# from the given array with maximum sum
def longestSubWithMaxSum(arr, N):
 
    # Stores the largest element
    # of the array
    Max = max(arr)
 
    # If Max is less than 0
    if (Max < 0) :
 
        # Print the largest element
        # of the array
        print(Max)
        return
 
    # Traverse the array
    for i in range(N):
 
        # If arr[i] is greater
        # than or equal to 0
        if (arr[i] >= 0) :
 
            # Print elements of
            # the subsequence
            print(arr[i], end = " ")
 
# Driver code
arr = [ 1, 2, -4, -2, 3, 0 ]
 
N = len(arr)
 
longestSubWithMaxSum(arr, N)
 
# This code is contributed divyeshrabadiya07

C#

// C# program to implement
// the above approach
using System;
 
class GFG{
  
// Function to find the longest subsequence
// from the given array with maximum sum
static void longestSubWithMaxSum(int []arr,
                                 int N)
{
     
    // Stores the largest element
    // of the array
    int Max = arr[0];
     
    for(int i = 1; i < N; i++)
    {
        if (Max < arr[i])
            Max = arr[i];
    }
     
    // If Max is less than 0
    if (Max < 0)
    {
         
        // Print the largest element
        // of the array
        Console.Write(Max);
        return;
    }
     
    // Traverse the array
    for(int i = 0; i < N; i++)
    {
         
        // If arr[i] is greater
        // than or equal to 0
        if (arr[i] >= 0)
        {
             
            // Print elements of
            // the subsequence
            Console.Write(arr[i] + " ");
        }
    }
}
  
// Driver Code
public static void Main(String[] args)
{
    int []arr = { 1, 2, -4, -2, 3, 0 };
    int N = arr.Length;
  
    longestSubWithMaxSum(arr, N);
}
}
 
// This code is contributed by aashish1995

Javascript

 
// JavaScript program to implement
// the above approach
 
// Function to find the longest subsequence
// from the given array with maximum sum
function longestSubWithMaxSum(arr, N)
{    
     
    // Stores the largest element
    // of the array
    let Max = Math.max(...arr);
   
    // If Max is less than 0
    if (Max < 0)
    {
          
        // Print the largest element
        // of the array
        document.write(Max);
        return;
    }
   
    // Traverse the array
    for(let i = 0; i < N; i++)
    {
          
        // If arr[i] is greater
        // than or equal to 0
        if (arr[i] >= 0)
        {
              
            // Print the elements of
            // the subsequence
            document.write(arr[i] + " ");
        }
    }
}
  
// Driver code
let arr = [ 1, 2, -4, -2, 3, 0 ];
let N = arr.length;
 
longestSubWithMaxSum(arr, N);
 
// This code is contributed by avijitmondal1998
 

输出：

1 2 3 0

时间复杂度： O(N)
辅助空间： O(1)