剑指 Offer 53 - I:在排序数组中查找数字 I

src/main/java/leetcode/editor/cn/ZaiPaiXuShuZuZhongChaZhaoShuZiLcof.java

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+//统计一个数字在排序数组中出现的次数。 
+//
+// 
+//
+// 示例 1: 
+//
+// 输入: nums = [5,7,7,8,8,10], target = 8
+//输出: 2 
+//
+// 示例 2: 
+//
+// 输入: nums = [5,7,7,8,8,10], target = 6
+//输出: 0 
+//
+// 
+//
+// 限制： 
+//
+// 0 <= 数组长度 <= 50000 
+//
+// 
+//
+// 注意：本题与主站 34 题相同（仅返回值不同）：https://leetcode-cn.com/problems/find-first-and-last-
+//position-of-element-in-sorted-array/ 
+// Related Topics 数组 二分查找 
+// 👍 179 👎 0
+
+package leetcode.editor.cn;
+
+//剑指 Offer 53 - I:在排序数组中查找数字 I
+class ZaiPaiXuShuZuZhongChaZhaoShuZiLcof {
+    public static void main(String[] args) {
+        //测试代码
+        Solution solution = new ZaiPaiXuShuZuZhongChaZhaoShuZiLcof().new Solution();
+        System.out.println(solution.search(new int[]{5, 7, 7, 8, 8, 10}, 6));
+        System.out.println(solution.search(new int[]{5, 7, 7, 8, 8, 10}, 8));
+    }
+
+    //力扣代码
+    //leetcode submit region begin(Prohibit modification and deletion)
+    class Solution {
+        public int search(int[] nums, int target) {
+            int start = binarySearch(nums, target, true);
+            int end = binarySearch(nums, target, false) - 1;
+            if (start <= end && end < nums.length && nums[start] == target && nums[end] == target) {
+                return end - start + 1;
+            }
+            return 0;
+        }
+
+        public int binarySearch(int[] nums, int target, boolean lower) {
+            int start = 0, end = nums.length - 1, ans = nums.length;
+            while (start <= end) {
+                int mid = (start + end) / 2;
+                if (nums[mid] > target || (lower && nums[mid] >= target)) {
+                    end = mid - 1;
+                    ans = mid;
+                } else {
+                    start = mid + 1;
+                }
+            }
+            return ans;
+        }
+    }
+//leetcode submit region end(Prohibit modification and deletion)
+
+}

src/main/java/leetcode/editor/cn/ZaiPaiXuShuZuZhongChaZhaoShuZiLcof.md

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+<p>统计一个数字在排序数组中出现的次数。</p>
+
+<p>&nbsp;</p>
+
+<p><strong>示例 1:</strong></p>
+
+<pre><strong>输入:</strong> nums = [<code>5,7,7,8,8,10]</code>, target = 8
+<strong>输出:</strong> 2</pre>
+
+<p><strong>示例&nbsp;2:</strong></p>
+
+<pre><strong>输入:</strong> nums = [<code>5,7,7,8,8,10]</code>, target = 6
+<strong>输出:</strong> 0</pre>
+
+<p>&nbsp;</p>
+
+<p><strong>限制：</strong></p>
+
+<p><code>0 &lt;= 数组长度 &lt;= 50000</code></p>
+
+<p>&nbsp;</p>
+
+<p><strong>注意：</strong>本题与主站 34 题相同（仅返回值不同）：<a href="https://leetcode-cn.com/problems/find-first-and-last-position-of-element-in-sorted-array/">https://leetcode-cn.com/problems/find-first-and-last-position-of-element-in-sorted-array/</a></p>
+<div><div>Related Topics</div><div><li>数组</li><li>二分查找</li></div></div>\n<div><li>👍 179</li><li>👎 0</li></div>