Time: 6 ms (11.57%), Space: 7.4 MB (56.93%) - LeetHub

Author: JanaSabuj

couples-holding-hands/couples-holding-hands.cpp

@@ -0,0 +1,61 @@
+struct dsu {
+    vector<int> parent;
+    vector<int> _size;
+
+    // merge two sets having a&b as entities
+    void union_sets(int a, int b) {
+        a = find_set(a);
+        b = find_set(b);
+        if (a != b) {
+            if (_size[a] < _size[b])
+                swap(a, b);
+            parent[b] = a;
+            _size[a] += _size[b];
+        }
+    }
+
+    // find the set leader
+    int find_set(int v) {
+        if (v == parent[v])
+            return v;
+        return parent[v] = find_set(parent[v]);
+    }
+
+    // check if same set/leader
+    bool same_comp(int a, int b) {
+        return find_set(a) == find_set(b);
+    }
+
+    void make_set(int v) {
+        parent[v] = v;
+        _size[v] = 1;
+    }
+
+    void _init(int n) {
+        parent.assign(n, 0);
+        _size.assign(n, 0);
+
+        for (int i = 0; i < n; i++)
+            make_set(i);
+    }
+};
+
+class Solution {
+public:
+    int minSwapsCouples(vector<int>& row) {
+        int n = row.size();
+        n /= 2;
+
+        dsu D;
+        D._init(n + 1);
+        int ccs = n;
+        for (int i = 0; i < 2 * n; i += 2){
+            if(D.find_set(row[i]/2) != D.find_set(row[i+1]/2)){
+                D.union_sets(row[i]/2, row[i+1]/2);
+                ccs--;
+            }
+        }
+
+        return (n - ccs);
+    }
+};