34. Search for a Range

使用二分找到target后，在两侧分别使用二分找到起点和终点。

class Solution {
    public int[] searchRange(int[] nums, int target) {
        int lo = 0 ;
        int hi = nums.length-1;
        int pos = -1;
        while(lo<=hi)
        {
             int mid = lo+(hi-lo)/2;
            if(nums[mid]==target)
            {
                pos=mid;
                break;
            }
            else if(nums[mid]<target)
            {
                lo=mid+1;
            }
            else
                hi=mid-1;
        }
        int[] result = new int[2];
        if(pos==-1)
        {
            result[0]=-1;
            result[1]=-1;
            return result;
        }
         lo = 0;
         hi=pos;
        while(lo<=hi)
        {
           int mid = lo+(hi-lo)/2;
           if(nums[mid]<target)
            {
                lo=mid+1;
            }
            else
                hi=mid-1;
        }
        int start =lo;
        
        
         lo = pos;
         hi=nums.length-1;
        while(lo<=hi)
        {
           int mid = lo+(hi-lo)/2;
           if(nums[mid]>target)
            {
                hi=mid-1;
            }
            else
                lo=mid+1;
        }
        int end =lo-1;
        
        
        result[0]=start;
        result[1]=end;
        return result;
        
    }
}