Min-Heap Insert (Sift Up)

Insert one value into a min-heap and restore the parent-child order by sifting upward.

Algorithm

@steps

Store the heap in an array.
Compare parent and child indexes instead of building explicit tree nodes.
Swap only when the heap order is violated.
Print the deterministic final heap state for replay comparison. @end @complexity

Time: O(log n)
Space: O(1) extra @end

sift up A new value starts at the end of the array and swaps with its parent while it is smaller.

Go DSA Implementation

basic.go

package main
import (
    "fmt"
    "strings"
)
func listString(values []int) string {
    parts := make([]string, len(values))
    for i, value := range values { parts[i] = fmt.Sprint(value) }
    return "[" + strings.Join(parts, ", ") + "]"
}
func heapInsert(heap *[]int, value int) {
    *heap = append(*heap, value)
    child := len(*heap) - 1
    for child > 0 {
        parent := (child - 1) / 2
        if (*heap)[parent] <= (*heap)[child] { break }
        (*heap)[parent], (*heap)[child] = (*heap)[child], (*heap)[parent]
        child = parent
    }
}
func heapPop(heap *[]int) int {
    smallest := (*heap)[0]
    (*heap)[0] = (*heap)[len(*heap)-1]
    *heap = (*heap)[:len(*heap)-1]
    parent := 0
    for {
        left := parent*2 + 1
        right := left + 1
        if left >= len(*heap) { break }
        child := left
        if right < len(*heap) && (*heap)[right] < (*heap)[left] { child = right }
        if (*heap)[parent] <= (*heap)[child] { break }
        (*heap)[parent], (*heap)[child] = (*heap)[child], (*heap)[parent]
        parent = child
    }
    return smallest
}
func main() { heap := []int{2, 4, 7, 9, 6}; heapInsert(&heap, 1); fmt.Println(listString(heap)) }

@end @output [1, 4, 2, 9, 6, 7] @end