fixed Code quality and added docs

data_structures/disjoint_set.cpp

@@ -1,3 +1,24 @@
+/**
+ *
+ * \file
+ * \brief [Disjoint Sets Data Structure
+ * (Disjoint Sets)](https://en.wikipedia.org/wiki/Disjoint-set_data_structure)
+ *
+ * \author
+ *
+ * \details
+ * A disjoint set data structure (also called union find or merge find set)
+ * is a data structure that tracks a set of elements partitioned into a number
+ * of disjoint (non-overlapping) subsets.
+ * Some situations where disjoint sets can be used are-
+ * to find connected components of a graph, kruskal's algorithm for finding
+ * Minimum Spanning Tree etc.
+ * There are two operation which we perform on disjoint sets -
+ * 1) Union
+ * 2) Find
+ *
+ */
+
 #include <iostream>
 #include <vector>
 
@@ -5,16 +26,30 @@ using std::cout;
 using std::endl;
 using std::vector;
 
-vector<int> root, rnk;
+vector<int> root, rank;
 
+/** 
+ * 
+ * Function to create a set
+ * @param n number of element
+ *
+ */
 void CreateSet(int n) {
     root = vector<int>(n + 1);
-    rnk = vector<int>(n + 1, 1);
+    rank = vector<int>(n + 1, 1);
     for (int i = 1; i <= n; ++i) {
         root[i] = i;
     }
 }
 
+/**
+ *
+ * Find operation takes a number x and returns the set to which this number
+ * belongs to.
+ * @param x element of some set
+ * @return set to which x belongs to
+ *
+ */
 int Find(int x) {
     if (root[x] == x) {
         return x;
@@ -22,22 +57,39 @@ int Find(int x) {
     return root[x] = Find(root[x]);
 }
 
+/** 
+ *
+ * A utility function to check if x and y are from same set or not
+ * @param x element of some set
+ * @param y element of some set
+ *
+ */
 bool InSameUnion(int x, int y) { return Find(x) == Find(y); }
 
+/**
+ *
+ * Union operation combines two disjoint sets to make a single set
+ * in this union function we pass two elements and check if they are
+ * from different sets then combine those sets
+ * @param x element of some set
+ * @param y element of some set
+ *
+ */
 void Union(int x, int y) {
     int a = Find(x), b = Find(y);
     if (a != b) {
-        if (rnk[a] < rnk[b]) {
+        if (rank[a] < rank[b]) {
             root[a] = b;
-        } else if (rnk[a] > rnk[b]) {
+        } else if (rank[a] > rank[b]) {
             root[b] = a;
         } else {
             root[a] = b;
-            ++rnk[b];
+            ++rank[b];
         }
     }
 }
 
+/** Main function */
 int main() {
     // tests CreateSet & Find
     int n = 100;