劍指 Offer 53 - I. 在排序數組中查找數字 I
統計一個數字在排序數組中出現的次數。
示例 1:
輸入: nums = [5,7,7,8,8,10], target = 8
輸出: 2
示例 2:
輸入: nums = [5,7,7,8,8,10], target = 6
輸出: 0
提示:
0 <= nums.length <= 105
-109 <= nums[i] <= 109
nums 是一個非遞減數組
-109 <= target <= 109
代碼
class Solution {
public:
int helper(vector<int>& nums, int target, int left, int right)
{
while(left <= right)
{
int mid = (left + right) / 2;
if (nums[mid] <= target) {
left = mid + 1;
} else {
right = mid - 1;
}
}
return left;
}
int search(vector<int>& nums, int target) {
int nlen = nums.size();
return helper(nums, target, 0, nlen - 1) - helper(nums, target - 1, 0, nlen - 1);
}
};