If you below purple, learn binary search first.

above purple you might add segment tree and BIT

It depends on your rating. While you are green, you'll never use segment tree or dsu on codeforces. Binary search and simple olympiad math are more relevant at this point.

permutation tree https://codeforces.com/blog/entry/78898

vector and set.

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If you're less than specialist i will tell you what templates will help you become specialist like me: Suffix automaton All geometric algorithms Max flow algos Heavy light decomp is a must Link cut trees Rotation trees Treaps Sqrt tree Wavelet tree Recently elegia published some algo so new problems on that might come up in upcoming div2 B/C Divide and conquer fft and polynomial approximation algorithms And dont study binary search until you become an IGM cuz its a very hard topic and problems on it are kinda rare

Just sharing the templates you can save:

1. Permutations and Combinations template (n choose p and stuff) with support for inverses.

2. Disjoin Set Union (or Union Find)

3. Templates for working with Primes (Sieve, Primality Check and stuff), factors (smallest prime factor), and Euler Totient Function.

4. Lowest Common Ancestor template for Tree

5. Hashing Template for Strings (like Polynomial rolling hash)

6. Fenwick Tree and Segment Tree for updates and queries.

These are not specific to any Color, just having them handy will be good. Usually, when I am stuck on a problem, I check the next ones. Sometimes one/two such problems seem familiar — having templates handy will save time.

This YouKn0wWho's collection was once recommended to me by a friend, but I never used it. I code from the scratch, most of the time.

Every code I can put in a C++ struct I do:

My snippets: https://github.com/MuhammadSawalhy/problem-solving/blob/main/cpp.snippets

    struct Trie {
        vector<vector<int>> child;
        vector<int> count;

        Trie() {
            add_node();
        }

        int add_node() {
            count.push_back(0);
            child.push_back(vector<int>(26));
            return count.size() - 1;
        }

        void insert(const string &s) {
            int cur = 0; // root
            for (auto c: s) {
                if (child[cur][c - 'a'] == 0)
                    child[cur][c - 'a'] = add_node();
                cur = child[cur][c - 'a'];
                count[cur]++;
            }
        }
    };

You should have other templates like input or other things that will help you solve problems quicker. Best way to get to specialist :D

Not exactly data structure, but I find having input mock useful for interactive problems.