From c8863c7ca6ab2b1cb9a6b5db50c747e05b12754e Mon Sep 17 00:00:00 2001
From: wangzongxu <308929264@qq.com>
Date: Thu, 4 Mar 2021 17:42:38 +0800
Subject: [PATCH] Update KthNum.js
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L11：因为要求是求第K大的数，由于分区是从小到大排序，第K大的数就是第 len - (k - 1) 小的数；
L14：如果基准点到了第一个或者最后一个，也就是说已经把三份的数组分成了两份，说明已经从小到大排序完成了，这时直接根据要求，给出第k个即可
---
 javascript/12_sorts/KthNum.js | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/javascript/12_sorts/KthNum.js b/javascript/12_sorts/KthNum.js
index 328b62c2..9c26e418 100644
--- a/javascript/12_sorts/KthNum.js
+++ b/javascript/12_sorts/KthNum.js
@@ -8,8 +8,12 @@ function kthNum(arr, k) {
   if (k > len) {
     return -1;
   }
+  k = len - (k - 1)
   let p = partition(arr, 0, len - 1);
   while (p + 1 !== k) {
+    if (p === 0 || p === arr.length - 1) {
+      return arr[k - 1]
+    }
     if (p + 1 > k) {
       p = partition(arr, 0, p - 1);
     } else {