algorithm/leetcode-master
1
0
Fork 0
mirror of https://github.com/youngyangyang04/leetcode-master.git synced 2025-07-07 15:45:40 +08:00
Code Issues Packages Projects Releases Wiki Activity

Merge pull request #1190 from effycoco/master

Browse Source 
Update 0704.二分查找.md
This commit is contained in:
程序员Carl
2022-04-17 11:33:45 +08:00
committed by GitHub
parent fb8adb4967 c4a4a03231
commit 7bc8e6534f
1 changed files with 10 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

13
problems/0704.二分查找.md
View File

@ -276,7 +276,7 @@ func search(nums []int, target int) int {
```
**JavaScript:**
（版本一）左闭右闭区间
（版本一）左闭右闭区间 [left, right]
```js
/**
@ -285,10 +285,12 @@ func search(nums []int, target int) int {
* @return {number}
*/
var search = function(nums, target) {
// right是数组最后一个数的下标，num[right]在查找范围内，是左闭右闭区间
let left = 0, right = nums.length - 1;
// 使用左闭右闭区间
// 当left=right时，由于nums[right]在查找范围内，所以要包括此情况
while (left <= right) {
let mid = left + Math.floor((right - left)/2);
// 如果中间数大于目标值，要把中间数排除查找范围，所以右边界更新为mid-1；如果右边界更新为mid，那中间数还在下次查找范围内
if (nums[mid] > target) {
right = mid - 1; // 去左面闭区间寻找
} else if (nums[mid] < target) {
@ -300,7 +302,7 @@ var search = function(nums, target) {
return -1;
};
```
（版本二）左闭右开区间
（版本二）左闭右开区间 [left, right)
```js
/**
@ -309,10 +311,13 @@ var search = function(nums, target) {
* @return {number}
*/
var search = function(nums, target) {
// right是数组最后一个数的下标+1，nums[right]不在查找范围内，是左闭右开区间
let left = 0, right = nums.length;
// 使用左闭右开区间 [left, right)
// 当left=right时，由于nums[right]不在查找范围，所以不必包括此情况
while (left < right) {
let mid = left + Math.floor((right - left)/2);
// 如果中间值大于目标值，中间值不应在下次查找的范围内，但中间值的前一个值应在；
// 由于right本来就不在查找范围内，所以将右边界更新为中间值，如果更新右边界为mid-1则将中间值的前一个值也踢出了下次寻找范围
if (nums[mid] > target) {
right = mid; // 去左区间寻找
} else if (nums[mid] < target) {