2024/11/12 灵茶题单 二分查找

src/main/java/com/cool/ling_cha_mount/binary_search/Num2529.java

@@ -0,0 +1,46 @@
+package com.cool.ling_cha_mount.binary_search;
+
+import org.junit.Test;
+
+/**
+ * @author : Cool
+ * @date: 2024/11/12
+ */
+public class Num2529 {
+    /**
+     * @Author Cool
+     * @Date 18:50 2024/11/12
+     * 找到第一个0，若存在则找最后一个0的位置，类似于<a herf="https://leetcode.cn/problems/find-first-and-last-position-of-element-in-sorted-array/description/"/>
+     * 若找不到0，则可能是数组内所有数字都小于0，或是不存在0，则进行分类讨论
+     **/
+    public int maximumCount(int[] nums) {
+        int start = binarySearch(nums, 0);
+        if (start < nums.length && nums[start] == 0) {
+            int end = binarySearch(nums, 1) - 1;
+            return Math.max(start, nums.length - end - 1);
+        }
+        if (start < nums.length) {
+            return Math.max(start, nums.length - start);
+        }
+        return nums.length;
+    }
+
+    private int binarySearch(int[] nums, int target) {
+        int left = 0;
+        int right = nums.length - 1;
+        while (left <= right) {
+            int mid = left + (right - left) / 2;
+            if (target <= nums[mid]) {
+                right = mid - 1;
+            } else {
+                left = mid + 1;
+            }
+        }
+        return left;
+    }
+
+    @Test
+    public void test() {
+        maximumCount(new int[]{-2, -1, -1, 1, 2, 3});
+    }
+}