二分查找法 C#实现

2015/09/20 69470

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public int FindPosition(int num, int[] arr) 
        { 
            int left = 0; 
            int right = arr.Length - 1; 
   
   
            while (left < right - 1) 
            { 
                if (arr[left] == num) 
                { 
                    return left; 
                } 
                if (arr[right] == num) 
                { 
                    return right; 
                } 
   
   
                int middle = (left + right) / 2; 
                if (num == arr[middle]) 
                { 
                    return middle; 
                } 
                else if (num < arr[middle]) 
                { 
                    right = middle; 
                } 
                else 
                { 
                    left = middle; 
                } 
   
   
            } 
            return -1; 
        }