剑指 Offer 53-I. 在排序数组中查找数字 I
题目
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
提示:
- 0 <= nums.length <= 105
- -109 <= nums[i]<= 109
- nums是一个非递减数组
- -109 <= target <= 109
注意: 本题与主站34题相同(仅返回值不同)
题解
public int search(int[] nums, int target) {
// 二分查找
BiFunction<Integer, Integer, Integer> binarySearch = new BiFunction<Integer, Integer, Integer>() {
@Override
public Integer apply(Integer start, Integer end) {
if (start > end || nums[end] < target || nums[start] > target) {
return 0;
}
if (nums[end] == target || nums[start] == target) {
int count = 0;
for (int i = start; i <= end; i++) {
count += nums[i] == target ? 1 : 0;
}
return count;
}
int mid = (start + end) >> 1;
return this.apply(start, mid) + this.apply(mid + 1, end);
}
};
return binarySearch.apply(0, nums.length - 1);
}