Two Sum III - Data structure design
170. Two Sum III - Data structure design
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
public class TwoSum {
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) {
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 i : map.keySet()) {
int target = value - i;
if (map.containsKey(target)) {
if (target != i) {
return true;
} else {
if (map.get(i) > 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);
*/
Hope this helps,
Michael