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| class Solution {
private static class UnionFind {
private final int[] parent;
public UnionFind(int n) {
this.parent = new int[n];
for (int i = 0; i < parent.length; i++) {
parent[i] = i;
}
}
public void union(int x, int y) {
int xRoot = getRoot(x), yRoot = getRoot(y);
if (xRoot == yRoot) {
return;
}
parent[xRoot] = yRoot;
}
private int getRoot(int x) {
if (parent[x] != x) {
parent[x] = getRoot(parent[x]);
}
return parent[x];
}
}
public int countServers(int[][] grid) {
int m = grid.length, n = grid[0].length;
UnionFind unionFind = new UnionFind(m * n);
for (int i = 0; i < m; i++) {
for (int j = 0; j < n; j++) {
if (grid[i][j] == 1) {
for (int k = j + 1; k < n; k++) {
if (grid[i][k] == 1) {
unionFind.union(toIndex(n, i, j), toIndex(n, i, k));
}
}
break;
}
}
}
for (int j = 0; j < n; j++) {
for (int i = 0; i < m; i++) {
if (grid[i][j] == 1) {
for (int k = i + 1; k < m; k++) {
if (grid[k][j] == 1) {
unionFind.union(toIndex(n, i, j), toIndex(n, k, j));
}
}
break;
}
}
}
Map<Integer, Integer> rootToCountMap = new HashMap<>();
for (int i = 0; i < m; i++) {
for (int j = 0; j < n; j++) {
if (grid[i][j] == 1) {
int root = unionFind.getRoot(toIndex(n, i, j));
rootToCountMap.put(root, rootToCountMap.getOrDefault(root, 0) + 1);
}
}
}
int count = 0;
for (int cellCount : rootToCountMap.values()) {
if (cellCount > 1) {
count += cellCount;
}
}
return count;
}
private int toIndex(int n, int i, int j) {
return i * n + j;
}
}
|