leetcode34

class Solution {
public:
    vector<int> searchRange(vector<int>& nums, int target)
    {
        vector<int> r(2, -1);
        if (!nums.size())
        {
            return r;//为空时，返回[-1,-1]        
        }
        int l = 0, h = nums.size() - 1, m = 0;
        if (target < nums[l] || nums[h] < target)
        {
            return r; //小于最小或大于最大返回[-1,-1]        
        }
        while (l <= h)
        {
            m = (l + h) / 2;
            if (nums[m] == target)
            {
                //命中m时                
                int i = m;
                while (nums[i] == target&&i < nums.size())
                {
                    i++;//寻找nums中与target相等值的右界                
                }
                r[1] = i - 1;
                while (nums[m] == target&&m >= 0)
                {
                    m--;//寻找nums中与target相等值的左界                
                }
                r[0] = m + 1;
                return r;
            }
            else if (nums[m] < target)
            {
                l = m + 1;
            }
            else
            {
                h = m - 1;
            }
        }
        return r;//没找到target，返回[-1,-1]    
    }
};

补充一个python的实现：

class Solution:
    def searchRange(self, nums: 'List[int]', target: 'int') -> 'List[int]':
        n = len(nums)
        i = 0
        j = n - 1
        if i == j:
            if nums[i] == target:
                return [0,0]
            else:
                return [-1,-1]
        begin = 0
        end = n - 1
        while i < j:
            if nums[i] == target:
                begin = i
                end = i
                while end < n and nums[end] == target:
                    end += 1
                return [begin,end-1]
            if nums[j] == target:
                end = j
                begin = j
                while begin >= 0 and nums[begin] == target:
                    begin -= 1
                return [begin+1,end]
            mid = i + (j - i) // 2
            if nums[mid] == target:
                begin = mid
                while begin >= 0 and nums[begin] == target:
                    begin -= 1
                end = mid
                while end < n and nums[end] == target:
                    end += 1
                return [begin+1,end-1]
            elif nums[mid] < target:
                i = mid + 1
            else:
                j = mid - 1
        return [-1,-1]