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ProcessRestrictedFriendRequests.java
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/*https://leetcode.com/problems/process-restricted-friend-requests/*/
class Solution {
public boolean[] friendRequests(int n, int[][] restrictions, int[][] requests) {
int[] parents = IntStream.rangeClosed(0,n-1).toArray();
Map<Integer,Set<Integer>> sets = new HashMap<Integer,Set<Integer>>();
for (int i = 0; i < n; ++i)
{
sets.put(i,new HashSet<Integer>());
sets.get(i).add(i);
}
int requestsLength = requests.length;
boolean[] result = new boolean[requestsLength];
for (int i = 0; i < requestsLength; ++i)
result[i] = union(parents,sets,restrictions,requests[i][0],requests[i][1]);
return result;
}
private boolean union(int[] parents, Map<Integer,Set<Integer>> sets, int[][] restrictions, int x, int y)
{
int parentX = find(parents,x);
int parentY = find(parents,y);
if (parentX != parentY)
{
Set<Integer> setX = sets.get(parentX);
Set<Integer> setY = sets.get(parentY);
for (int[] restriction : restrictions)
{
if ((setX.contains(restriction[0]) && setY.contains(restriction[1])) || (setX.contains(restriction[1]) && setY.contains(restriction[0])))
return false;
}
if (setX.size() > setY.size())
{
parents[parentY] = parentX;
sets.remove(parentY);
setX.addAll(setY);
}
else
{
parents[parentX] = parentY;
sets.remove(parentX);
setY.addAll(setX);
}
}
return true;
}
private int find(int[] parents, int x)
{
if (parents[x] == x) return x;
parents[x] = find(parents,parents[x]);
return parents[x];
}
}
class Solution {
public boolean[] friendRequests(int n, int[][] restrictions, int[][] requests) {
int[] parents = IntStream.rangeClosed(0,n-1).toArray();
int[] rank = new int[n];
int requestsLength = requests.length;
boolean[] result = new boolean[requestsLength];
for (int i = 0; i < requestsLength; ++i)
result[i] = union(parents,rank,restrictions,requests[i][0],requests[i][1]);
return result;
}
private boolean union(int[] parents, int[] rank, int[][] restrictions, int x, int y)
{
int parentX = find(parents,x);
int parentY = find(parents,y);
if (parentX != parentY)
{
for (int[] restriction : restrictions)
{
int parentRestrictedX = find(parents,restriction[0]);
int parentRestrictedY = find(parents,restriction[1]);
if ((parentX == parentRestrictedX && parentY == parentRestrictedY) || (parentX == parentRestrictedY && parentY == parentRestrictedX))
return false;
}
if (rank[parentX] > rank[parentY])
parents[parentY] = parentX;
else
{
parents[parentX] = parentY;
if (rank[parentX] == rank[parentY])
++rank[parentY];
}
}
return true;
}
private int find(int[] parents, int x)
{
if (parents[x] == x) return x;
parents[x] = find(parents,parents[x]);
return parents[x];
}
}
class Solution {
public boolean[] friendRequests(int n, int[][] restrictions, int[][] requests) {
int[] parents = IntStream.rangeClosed(0,n-1).toArray();
int[] rank = new int[n];
int requestsLength = requests.length;
boolean[] result = new boolean[requestsLength];
boolean[][] enemies = new boolean[n][n];
for (int[] restriction : restrictions)
enemies[restriction[0]][restriction[1]] = enemies[restriction[1]][restriction[0]] = true;
for (int i = 0; i < requestsLength; ++i)
result[i] = union(parents,rank,enemies,n,requests[i][0],requests[i][1]);
return result;
}
private boolean union(int[] parents, int[] rank, boolean[][] restrictions, int n, int x, int y)
{
int parentX = find(parents,x);
int parentY = find(parents,y);
if (parentX != parentY)
{
if (restrictions[parentX][parentY])
return false;
if (rank[parentX] > rank[parentY])
parents[parentY] = parentX;
else
{
parents[parentX] = parentY;
if (rank[parentX] == rank[parentY])
++rank[parentY];
}
for (int i = 0; i < n; ++i)
{
if (restrictions[parentX][i]) restrictions[parentY][i] = restrictions[i][parentY] = true;
if (restrictions[parentY][i]) restrictions[parentX][i] = restrictions[i][parentX] = true;
}
}
return true;
}
private int find(int[] parents, int x)
{
if (parents[x] == x) return x;
parents[x] = find(parents,parents[x]);
return parents[x];
}
}