Maximum sum subarray program in Go (Golang)

Overview

The objective is to find the maximum subarray in a given input array. The subarray should be contiguous and should contain at least one element

For example

Input: [4, 5 ,-3]
Maximum Subarray is [4, 5]
Output: 9

Another example

Input: [1, 2, -4, 4, 1]
Maximum Subarray is [4, 1]
Output: 5

We use the Kadane algorithm here. In the Kadane algorithm, we keep two variables max and currentMax

• max is initialized to IntMin and currentMax is initialized to zero

• Then we Loop for each element in the array
  • Set currentMax = currentMax + a[i]
  • If currentMax > max then max is set to currentMax
  • if currentMax is less than zero then currentMax is reset to zero

Program

Here is the program for the same

package main

import "fmt"

const (
	UintSize = 32 << (^uint(0) >> 32 & 1)
	MaxInt   = 1<<(UintSize-1) - 1 // 1<<31 - 1 or 1<<63 - 1
	MinInt   = -MaxInt - 1
)

func main() {
	input := []int{4, 5, -3}
	output := maxSubArray(input)
	fmt.Println(output)

	input = []int{1, 2, -4, 4, 1}
	output = maxSubArray(input)
	fmt.Println(output)
}

func maxSubArray(nums []int) int {
	lenNums := len(nums)

	currentMax := 0
	max := MinInt
	for i := 0; i < lenNums; i++ {
		currentMax = currentMax + nums[i]
		if currentMax > max {
			max = currentMax
		}

		if currentMax < 0 {
			currentMax = 0
		}

	}
	return max
}

Output

9
5

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