Two Sum III - Data structure design
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Total Submissions: 1345
Design and implement a TwoSum class. It should support the following operations:add
and
find
.
add
- Add the number to an internal data structure.
find
- Find if there exists any pair of numbers which sum is equal to the value.
For example,
add(1); add(3); add(5); find(4) -> true find(7) -> false [分析] HASH table O(N)存, O(1) 取public class TwoSum { Map<Integer, Integer> map = new HashMap<Integer, Integer>(); public void add(int number) { if(map.containsKey(number)) { map.put(number, map.get(number) + 1); } else { map.put(number, 1); } } public boolean find(int value) { for(int key : map.keySet()) { int another = value - key; if(another == key && map.get(key) > 1) { return true; } else if(another != key && map.containsKey(another)) { return true; } } return false; } }
时间: 2024-07-29 15:35:53