170.two-sum-iii-data-structure-design.java

/*
 * @lc app=leetcode id=170 lang=java
 *
 * [170] Two Sum III - Data structure design
 */

// @lc code=start
class TwoSum {
    private Map<Integer, Integer> map;
    /** Initialize your data structure here. */
    public TwoSum() {
        map = new HashMap<>();
    }
    
    /** Add the number to an internal data structure.. */
    public void add(int number) {
        map.put(number, map.getOrDefault(number, 0) + 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 num = value - key;
            if (num != key) {
                if (map.containsKey(num)) {
                    return true;
                }
            } else if (map.get(key) > 1) {
                    return true;
            }      
        }
        return false;
    }
}

/**
 * Your TwoSum object will be instantiated and called as such:
 * TwoSum obj = new TwoSum();
 * obj.add(number);
 * boolean param_2 = obj.find(value);
 */
// @lc code=end