59 lines
1.3 KiB
Go
59 lines
1.3 KiB
Go
package binarysearch
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import "strconv"
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// SearchInts searches a slice of ints for the first position that 'n' should
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// be inserted at and keep 'hay' sorted
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func SearchInts(hay []int, n int) int {
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if len(hay) == 0 || n < hay[0] {
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return 0
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}
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if n > hay[len(hay)-1] {
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return len(hay)
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}
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mid := len(hay) / 2
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if hay[mid] < n {
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return mid + 1 + SearchInts(hay[mid+1:], n)
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}
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if n < hay[mid] {
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return SearchInts(hay[:mid], n)
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}
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for mid > 0 && hay[mid-1] == n {
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mid--
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}
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return mid
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}
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// Message does the binary search and returns an english string representation
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// of the result
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func Message(hay []int, n int) string {
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if len(hay) == 0 {
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return "slice has no values"
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}
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v := SearchInts(hay, n)
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if v < len(hay) && hay[v] == n {
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switch v {
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case 0:
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return itoa(n) + " found at beginning of slice"
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case len(hay) - 1:
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return itoa(n) + " found at end of slice"
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}
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return itoa(n) + " found at index " + itoa(v)
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}
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switch v {
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case 0:
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return itoa(n) + " < all values"
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case len(hay):
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return itoa(n) + " > all " + itoa(len(hay)) + " values"
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}
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return itoa(n) + " > " + itoa(hay[v-1]) + " at index " + itoa(v-1) + ", < " + itoa(hay[v]) + " at index " + itoa(v)
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}
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// itoa is because I'm tired of writing strconv.Itoa
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func itoa(v int) string {
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return strconv.Itoa(v)
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}
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