leetcode

Solution to some Leetcode problems written in C++
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1722.cpp (1240B)

      1 class UnionFind {
      2     int n, cnt = n;
      3     vector<int> root, size;
      4 
      5   public:
      6     UnionFind(int n) : n(n), root(n), size(n, 1) { iota(root.begin(), root.end(), 0); }
      7 
      8     int find(int x) {
      9         while (x != root[x])
     10             x = root[x] = root[root[x]];
     11         return x;
     12     }
     13 
     14     void join(int x, int y) {
     15         x = find(x), y = find(y);
     16         if (x != y) {
     17             if (size[x] > size[y]) swap(x, y);
     18             root[x] = y;
     19             size[y] += size[x];
     20             cnt--;
     21         }
     22     }
     23 
     24     int count() { return cnt; }
     25     bool connected(int x, int y) { return find(x) == find(y); }
     26 };
     27 
     28 class Solution {
     29   public:
     30     int minimumHammingDistance(vector<int> &source, vector<int> &target, vector<vector<int>> &allowedSwaps) {
     31         int n = source.size();
     32         UnionFind uf(n);
     33 
     34         for (auto &s : allowedSwaps)
     35             uf.join(s[0], s[1]);
     36 
     37         vector<unordered_map<int, int>> vus(n);
     38         for (int i = 0; i < n; i++) {
     39             int pos = uf.find(i);
     40             vus[pos][target[i]]++;
     41             vus[pos][source[i]]--;
     42         }
     43 
     44         int res = 0;
     45         for (int i = 0; i < n; i++)
     46             for (auto [_, val] : vus[i])
     47                 res += abs(val);
     48 
     49         return res / 2;
     50     }
     51 };