auto commit

notes/算法.md

@@ -115,21 +115,19 @@ public class ThreeSumFast {
 ```
 
 ```java
-public class ThreeSumFast implements ThreeSum {
-    @Override
-    public int count(int[] nums) {
-        Arrays.sort(nums);
-        int N = nums.length;
-        int cnt = 0;
-        for (int i = 0; i < N; i++)
-            for (int j = i + 1; j < N; j++) {
-                int target = -nums[i] - nums[j];
-                int index = BinarySearch.search(nums, target);
-                // 应该注意这里的下标必须大于 j，否则会重复统计。
-                if (index > j)
-                    cnt++;
-            }
-        return cnt;
+public class BinarySearch {
+    public static int search(int[] nums, int target) {
+        int l = 0, h = nums.length - 1;
+        while (l <= h) {
+            int m = l + (h - l) / 2;
+            if (target == nums[m])
+                return m;
+            else if (target > nums[m])
+                l = m + 1;
+            else
+                h = m - 1;
+        }
+        return -1;
     }
 }
 ```