修改 0704 二分查找 JavaScript版本解法

原解法逻辑不够简洁清晰，简单问题被其复杂化，所以我提出个人认为更简洁清晰的解法
tlylt · Sep 24, 2021 · 431b5a7 · 431b5a7
1 parent 0f0bb6e
commit 431b5a7
Showing 1 changed file with 32 additions and 17 deletions.
diff --git a/problems/0704.二分查找.md b/problems/0704.二分查找.md
@@ -283,31 +283,46 @@ func search(nums []int, target int) int {
 
 // （版本一）左闭右闭区间
 
+/**
+ * @param {number[]} nums
+ * @param {number} target
+ * @return {number}
+ */
 var search = function(nums, target) {
-    let l = 0, r = nums.length - 1;
-    // 区间 [l, r]
-    while(l <= r) {
-        let mid = (l + r) >> 1;
-        if(nums[mid] === target) return mid;
-        let isSmall = nums[mid] < target;
-        l = isSmall ? mid + 1 : l;
-        r = isSmall ? r : mid - 1;
+    let left = 0, right = nums.length;
+    // 使用左闭右开区间 [left, right)
+    while (left < right) {
+        let mid = left + Math.floor((right - left)/2);
+        if (nums[mid] > target) {
+            right = mid;  // 去左区间寻找
+        } else if (nums[mid] < target) {
+            left = mid + 1;   // 去右区间寻找
+        } else {
+            return mid;
+        }
     }
     return -1;
 };
 
 // （版本二）左闭右开区间
 
+/**
+ * @param {number[]} nums
+ * @param {number} target
+ * @return {number}
+ */
 var search = function(nums, target) {
-    let l = 0, r = nums.length;
-    // 区间 [l, r）
-    while(l < r) {
-        let mid = (l + r) >> 1;
-        if(nums[mid] === target) return mid;
-        let isSmall = nums[mid] < target;
-        l = isSmall ? mid + 1 : l;
-        // 所以 mid 不会被取到
-        r = isSmall ? r : mid;
+    let left = 0, right = nums.length;
+    // 使用左闭右开区间 [left, right)
+    while (left < right) {
+        let mid = left + Math.floor((right - left)/2);
+        if (nums[mid] > target) {
+            right = mid;  // 去左区间寻找
+        } else if (nums[mid] < target) {
+            left = mid + 1;   // 去右区间寻找
+        } else {
+            return mid;
+        }
     }
     return -1;
 };