diff --git a/problems/0704.二分查找.md b/problems/0704.二分查找.md
index eec97a78..53f5331a 100644
--- a/problems/0704.二分查找.md
+++ b/problems/0704.二分查找.md
@@ -290,10 +290,11 @@ func search(nums []int, target int) int {
  */
 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;
+    let mid, left = 0, right = nums.length - 1;
     // 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);
+        // 位运算 + 防止大数溢出
+        mid = left + ((right - left) >> 1);
         // 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
@@ -316,10 +317,11 @@ var search = function(nums, target) {
  */
 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;    
+    let mid, left = 0, right = nums.length;    
     // 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);
+        // 位运算 + 防止大数溢出
+        mid = left + ((right - left) >> 1);
         // 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) {
@@ -340,9 +342,10 @@ var search = function(nums, target) {
 
 ```typescript
 function search(nums: number[], target: number): number {
-    let left: number = 0, right: number = nums.length - 1;
+    let mid: number, left: number = 0, right: number = nums.length - 1;
     while (left <= right) {
-        let mid: number = left + Math.floor((right - left) / 2);
+        // 位运算 + 防止大数溢出
+        mid = left + ((right - left) >> 1);
         if (nums[mid] > target) {
             right = mid - 1;
         } else if (nums[mid] < target) {
@@ -359,9 +362,10 @@ function search(nums: number[], target: number): number {
 
 ```typescript
 function search(nums: number[], target: number): number {
-    let left: number = 0, right: number = nums.length;
+    let mid: number, left: number = 0, right: number = nums.length;
     while (left < right) {
-        let mid: number = left + Math.floor((right - left) / 2);
+        // 位运算 + 防止大数溢出
+        mid = left +((right - left) >> 1);
         if (nums[mid] > target) {
             right = mid;
         } else if (nums[mid] < target) {