45 lines
1.2 KiB
Go
45 lines
1.2 KiB
Go
package arraysum
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// SumWithForLoop uses a for loop to
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// calculate the sum of the slice argument.
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func SumWithForLoop(numbers []int) int {
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output := 0
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for _, v := range numbers {
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output += v
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}
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return output
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}
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// SumWithRecursion uses recursion to
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// calculate the sum of the slice argument.
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func SumWithRecursion(numbers []int) int {
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if len(numbers) == 0 {
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return 0
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}
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return numbers[0] + SumWithRecursion(numbers[1:])
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}
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// SumWithRecursion uses tail recursion to
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// calculate the sum of the slice argument.
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func SumWithTailRecursion(numbers []int) int {
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return SumWithSubTailCall(numbers, 0)
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}
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// SumWithSubTailCall is a sub function of
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// SumWithTailRecursion. This function takes the
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// first element of the array and adds it to the
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// running total. It then removes said element and
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// calls itself with the updated slice and the current
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// running total.
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// Recursion ends when there are no more elements in the
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// slice. It returns the total sum back to the SubWithTailRecursion
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// function.
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func SumWithSubTailCall(numbers []int, runningTotal int) int {
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if len(numbers) == 0 {
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return runningTotal
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}
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runningTotal += numbers[0]
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return SumWithSubTailCall(numbers[1:], runningTotal)
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}
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