Problem
Leet code problem 881
Difficulty: Medium —
Solution
Implementation
Code from github
First approach (HashMap)
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public class L2441_LargestPositiveIntegerThatExistsWithItsNegative {
public static final int FOUND_BOTH_NEGATIVE_POSITIVE = 0;
public static final int FOUND_NEGATIVE = -1;
public static final int FOUND_POSITIVE = 1;
public int findMaxK(int[] nums) {
Map<Integer, Integer> resultMap = new HashMap();
for (int i = 0; i < nums.length; i++) {
if (nums[i] > 0) {
if (!resultMap.containsKey(nums[i])) {
resultMap.put(nums[i], FOUND_POSITIVE);
} else if (resultMap.get(nums[i]) == FOUND_NEGATIVE) {
resultMap.put(nums[i], FOUND_BOTH_NEGATIVE_POSITIVE);
}
} else {
if (!resultMap.containsKey(-nums[i])) {
resultMap.put(-nums[i], FOUND_NEGATIVE);
} else if (resultMap.get(-nums[i]) == FOUND_POSITIVE) {
resultMap.put(-nums[i], FOUND_BOTH_NEGATIVE_POSITIVE);
}
}
}
int max = -1;
for (Map.Entry<Integer, Integer> entry : resultMap.entrySet()) {
if (entry.getValue() == FOUND_BOTH_NEGATIVE_POSITIVE && max < entry.getKey()) {
max = entry.getKey();
}
}
return max;
}
}
Second approach (HashSet)
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public class L2441_LargestPositiveIntegerThatExistsWithItsNegative {
public int findMaxK(int[] nums) {
Set<Integer> resultSet = new HashSet<>();
for (int i = 0; i < nums.length; i++) {
resultSet.add(nums[i]);
}
int max = -1;
for (Integer item : resultSet) {
if (resultSet.contains(-item) && max < Math.abs(item)) {
max = Math.abs(item);
}
}
return max;
}
}