[LeetCode]Two Sum III - Data structure design

这道题我用O(n)存O(1)取的时候会超时,但是用O(1)存O(n)取就不会超时,个人觉得是因为测试代码中存比取要多得多。。

其实觉得最好的方法应该是O(logn)存取,用两个二分搜索,但是还没太想明白应该用什么数据结构能实现

public class TwoSum {
    
    private HashMap<Integer, Integer> map = new HashMap<Integer, Integer>();

    // Add the number to an internal data structure.
    public void add(int number) {
        if (map.containsKey(number)) {
            map.put(number, map.get(number) + 1);
        } else {
            map.put(number, 1);
        }
    }

    // Find if there exists any pair of numbers which sum is equal to the value.
    public boolean find(int value) {
        for (int key : map.keySet()) {
            int target = value - key;
            if (map.containsKey(target)) {
                if (target != key) {
                    return true;
                } else {
                    if (map.get(key) > 1) {
                        return true;
                    }
                }
            }
        }
        return false;
    }
}


// Your TwoSum object will be instantiated and called as such:
// TwoSum twoSum = new TwoSum();
// twoSum.add(number);
// twoSum.find(value);

 

posted @ 2015-11-27 06:44  Weizheng_Love_Coding  阅读(136)  评论(0编辑  收藏  举报