91 lines
1.5 KiB
Go
91 lines
1.5 KiB
Go
package binarySearch
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//查找第一个值等于给定值得元素
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func BinarySearch2(nums []int, value int) int {
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length := len(nums)
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start := 0
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end := length - 1
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for start <= end {
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mid := (start + end) / 2
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if nums[mid] > value {
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end = mid - 1
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} else if nums[mid] < value {
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start = mid + 1
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} else {
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for mid >= 0 {
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if nums[mid-1] == value {
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mid--
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} else {
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return mid
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}
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}
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}
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}
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return -1
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}
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// 查找最后一个值等于给定值的元素
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func BinarySearch3(nums []int, value int) int {
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start := 0
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end := len(nums) - 1
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for start <= end {
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mid := (start + end) / 2
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if nums[mid] > value {
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end = mid - 1
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} else if nums[mid] < value {
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start = mid + 1
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} else {
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for mid < len(nums) {
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if nums[mid+1] == value {
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mid++
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} else {
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return mid
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}
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}
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}
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}
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return -1
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}
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// 查找第一个大于等于给定值的元素
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func BinarySearch4(nums []int, value int) int {
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start := 0
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end := len(nums) - 1
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for start <= end {
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mid := (start + end) >> 1
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if nums[mid] < value {
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start = mid + 1
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} else {
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for mid >= 0 {
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if nums[mid-1] >= value {
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mid--
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} else {
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return mid
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}
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}
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}
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}
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return -1
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}
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// 查找最后一个小于等于给定值的元素
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func BinarySearch5(nums []int, value int) int {
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start := 0
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end := len(nums) - 1
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for start <= end {
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mid := (start + end) >> 1
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if nums[mid] > value {
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end = mid - 1
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} else {
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for mid < len(nums) {
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if nums[mid+1] <= value {
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mid++
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} else {
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return mid
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}
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}
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}
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}
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return -1
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}
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