Fix disjoint_set

Signed-off-by: Bruno Freitas Tissei <bft15@inf.ufpr.br>

structure/disjoint_set.cpp

@@ -9,13 +9,13 @@
  */
 
 int par[MAX];
-int rank[MAX];
+int h[MAX];
 int sz[MAX];
 
 // Initialize element x
 void make_set(int x) {
   par[x] = x;
-  rank[x] = 0;
+  h[x] = 0;
   sz[x] = 1;
 }
 
@@ -35,15 +35,15 @@ void union_set(int x, int y) {
   if (xroot == yroot)
     return;
 
-  if (rank[xroot] < rank[yroot]) {
+  if (h[xroot] < h[yroot]) {
     par[xroot] = yroot;
     sz[yroot] += sz[xroot];
-  } else if (rank[xroot] > rank[yroot]) {
+  } else if (h[xroot] > h[yroot]) {
     par[yroot] = xroot;
     sz[xroot] += sz[yroot];
   } else {
     par[yroot] = xroot;
     sz[xroot] += sz[yroot];
-    rank[xroot]++;
+    h[xroot]++;
   }
 }