Search-insert-position

最新推荐文章于 2021-07-27 23:40:38 发布

原创最新推荐文章于 2021-07-27 23:40:38 发布 · 320 阅读

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本文介绍了一种用于在已排序数组中查找目标值插入位置的方法。提供了两种实现方式：一种是直接搜索，另一种是使用二分搜索。这两种方法都能有效地找到目标值在数组中的正确位置或应该插入的位置。

题目描述

Given a sorted array and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order.

You may assume no duplicates in the array.

Here are few examples.
[1,3,5,6], 5 → 2
[1,3,5,6], 2 → 1
[1,3,5,6], 7 → 4
[1,3,5,6], 0 → 0

public class Solution {
    public int searchInsert(int[] A, int target) {
        int i = 0;
        for(i = 0 ; i < A.length ; i++)
        {
            if(target == A[i])
                 return i;
            else if(target < A[i])
                return i;
        }
        return A.length;
    }
}

or:

public class Solution {
    public int searchInsert(int[] A, int target) {
        int head = 0;
        int tail = A.length - 1;
        while(head <= tail)
        {
            int mid = (head + tail) / 2;
            if(A[mid] == target)
                return mid;
            else if(A[mid] > target)
                tail = mid - 1;
            else 
                head = mid + 1;;
        }
        return head;
    }
}

directly search or use the binary search