Discussions

Why does my solution TLE on the last test case? Use a hash map from value to index (or count). For each element check whether its complement is already in the map, then insert it. That makes it O(n) instead of the O(n²) brute force.

Asked in my Salesforce OA last week. Use a hash map from value to index (or count). For each element check whether its complement is already in the map, then insert it. That makes it O(n) instead of the O(n²) brute force.

Intuition + complexity breakdown for First Unique Character. Use a hash map from value to index (or count). For each element check whether its complement is already in the map, then insert it. That makes it O(n) instead of the O(n²) brute force.

Intuition + complexity breakdown for First Unique Character. Use a hash map from value to index (or count). For each element check whether its complement is already in the map, then insert it. That makes it O(n) instead of the O(n²) brute force.