查找第一个值等于给定值的元素

  1. function searchFirstEqualElement(nums, target) {
  2.   let len = nums.length
  3.   let low = 0
  4.   let high = len - 1
  5.   while(low < high) {
  6.     let mid = low + ((high - low) >> 1)
  7.     if(nums[mid] > target) {
  8.       high = mid - 1
  9.     } else if(nums[mid] < target) {
  10.       low = mid + 1
  11.     } else {
  12.       if(mid === 0 || nums[mid - 1] !== target) {
  13.         return mid
  14.       }
  15.       high = mid - 1
  16.     }
  17.   }
  18. }

查找最后一个值等于给定值的元素

  1. function searchLastEuqalElement(nums, target) {
  2.   let len = nums.length
  3.   let low = 0
  4.   let high = len - 1
  5.   while(low < high) {
  6.     let mid = low + ((high - low) >> 1)
  7.     if(nums[mid] > target) {
  8.       high = mid - 1
  9.     } else if (nums[mid] < target) {
  10.       low = mid + 1
  11.     } else {
  12.       if(mid === len - 1 || nums[mid + 1] !== target) {
  13.         return mid
  14.       }
  15.       low = mid + 1
  16.     }
  17.   }
  18. }

查找第一个大于等于给定值的元素

  1. function searchFirstGreaterElement(nums, target) {
  2.   let len = nums.length
  3.   let low = 0
  4.   let high = len - 1
  5.   while(low <= high) {
  6.     let mid = low + ((high - low) >> 1)
  7.     if(nums[mid] >= target) {
  8.       if(mid === 0 && nums[mid - 1] < target) {
  9.         return mid
  10.       }
  11.       high = mid - 1
  12.     } else {
  13.       low = mid + 1
  14.     }
  15.   }
  16. }

查找最后一个小于等于给定值的元素

  1. function searchLastLessElement(nums, target) {
  2.   let len = nums.length
  3.   let low = 0
  4.   let high = len - 1
  5.   while(low <= high) {
  6.     let mid = low + ((high - low) >> 1)
  7.     if(nums[mid] <= target) {
  8.       if(mid === len - 1 || nums[mid + 1] > target) {
  9.         return mid
  10.       }
  11.       low = mid + 1
  12.     } else {
  13.       high = mid - 1
  14.     }
  15.   }
  16. }