java - 二分查找实现java算法

Question

我在实现二分查找算法方面需要帮助，谁能告诉我我的代码有什么问题:

public int bsearch(Item idToSearch) { 
    int lowerBoundary = 0;
    int upperBoundary = myStore.size() - 1;
    int mid = -1;

    while(upperBoundary >= lowerBoundary) {
        mid = (lowerBoundary + upperBoundary) / 2;

        //if element at middle is less than item to be searched, than set new lower boundary to mid
        if(myStore.get(mid).compareTo(idToSearch) < 0) {
            lowerBoundary = mid - 1;
        } else {
            upperBoundary = mid + 1;
        }
    } //end while loop

    if(myStore.get(mid).equals(idToSearch)) {
        return mid;
    } else {
        return -1; // item not found
    }
} // end method

Answer 1

我认为你在更新 lowerBoundary 和 upperBoundary 时犯了一个错误。

可能是:

    if(myStore.get(mid).compareTo(idToSearch) < 0){
        lowerBoundary = mid + 1;
    } else {
        upperBoundary = mid - 1;
    }

如果在 mid 找到元素，为什么不中断循环？