From a32ff59676cad5ad791e6711023e5ff51fa873ab Mon Sep 17 00:00:00 2001
From: orgin <boyce.duan@gmail.com>
Date: Fri, 11 Nov 2022 14:17:29 +0800
Subject: [PATCH] =?UTF-8?q?=E4=BC=98=E5=8C=96=E4=BA=8C=E5=88=86=E6=9F=A5?=
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---
 util/algorithms/BiSearch.go | 29 +++++++++++++++++++----------
 1 file changed, 19 insertions(+), 10 deletions(-)

diff --git a/util/algorithms/BiSearch.go b/util/algorithms/BiSearch.go
index 5ed487b..c10fada 100644
--- a/util/algorithms/BiSearch.go
+++ b/util/algorithms/BiSearch.go
@@ -1,6 +1,5 @@
 package algorithms
 
-
 type NumberType interface {
 	int | int8 | int16 | int32 | int64 | string | float32 | float64 | uint | uint8 | uint16 | uint32 | uint64
 }
@@ -9,7 +8,15 @@ type Element[ValueType NumberType] interface {
 	GetValue() ValueType
 }
 
-//BiSearch 二分查找,切片必需有序号。matchUp表示是否向上范围查找。比如：数列10 20  30 ，当value传入25时，返回结果是2,表示落到3的范围
+/*
+BiSearch 二分查找,切片必需有序
+matchUp规则如下：
+参数为0时，则一定要找到相等的值
+参数-1时，找value左边的值，例如：[10,20,30,40],当value为9时返回-1; 当value为11时，返回0  当value为41时，返回 3
+参数 1时，找value右边的值，例如：[10,20,30,40],当value为9时返回 0; 当value为11时，返回1  当value为41时，返回-1
+
+返回-1时代表没有找到下标
+*/
 func BiSearch[ValueType NumberType, T Element[ValueType]](sElement []T, value ValueType, matchUp int) int {
 	low, high := 0, len(sElement)-1
 	if high == -1 {
@@ -30,24 +37,26 @@ func BiSearch[ValueType NumberType, T Element[ValueType]](sElement []T, value Va
 
 	switch matchUp {
 	case 1:
-		if (sElement[mid].GetValue()) < value &&
-			(mid+1 < len(sElement)-1) {
+		if (sElement[mid].GetValue()) < value {
+			if mid+1 >= len(sElement) {
+				return -1
+			}
 			return mid + 1
 		}
 		return mid
 	case -1:
 		if (sElement[mid].GetValue()) > value {
-			if mid - 1 < 0 {
+			if mid-1 < 0 {
 				return -1
 			} else {
 				return mid - 1
 			}
 		} else if (sElement[mid].GetValue()) < value {
-			if (mid+1 < len(sElement)-1) {
-				return mid + 1
-			} else {
-				return mid
-			}
+			//if mid+1 < len(sElement)-1 {
+			//	return mid + 1
+			//} else {
+			return mid
+			//}
 		} else {
 			return mid
 		}