代码随想录算法训练营第一天 | 704. 二分查找，27. 移除元素

 704. 二分查找

题目链接：https://leetcode.cn/problems/binary-search/

public int search(int[] nums, int target) {
        int low=0; 
        int high=nums.length-1;
        while(low<=high){
            int mid = (high+low)/2;
            if(nums[mid]==target){
                return mid;
            }
            else if(nums[mid]>target){
                high=mid-1;
            }
            else{
                low=mid+1;
            }
        }
        return -1;
    }

　　2. 左闭右开

public int search(int[] nums, int target) {
        int low=0;
        int high=nums.length;
        while(low<high)
        {
            int mid = (low + high)/2;
            if(nums[mid]==target)
            {
                return mid;
            }else if(nums[mid]>target)
            {
                high=mid;
            }else if(nums[mid]<target)
            {
                low=mid+1;
            }
        }
        return -1;
    }

27. 移除元素

题目链接：https://leetcode.cn/problems/remove-element/ 

暴力的解法:

    public static int deleteNum1(int[] arr, int deleteNum) {
        int size = arr.length;

        for (int i = 0; i < size; i++) {
            if (arr[i] == deleteNum) {
                for (int j = i + 1; j < size; j++) { 
                    arr[j - 1] = arr[j];
                }
                i--;  
                size--; 
            }
        }

        return size;
    }

双指针法:

  public int removeElement(int[] nums, int i) {
        int slow = 0;
        for (int fast = 0; fast < nums.length; fast++) {
            if (nums[fast] != i) {
                nums[slow++] = nums[fast];
            }
        }
        return slow;
    }