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| class Solution {
public void solve(char[][] board) {
int n1 = board.length;
if (n1 == 0) {
return;
}
int n2 = board[0].length;
int[] parent = new int[n1 * n2];
for (int i = 0; i < parent.length; i++) {
parent[i] = i;
}
for (int i = 0; i < n1-1; i++) {
for (int j = 1; j < n2; j++) {
if (board[i][j] == 'O' && board[i][j - 1] == board[i][j]) {
union(i * n2 + j, i * n2 + j - 1, parent);
}
if (board[i][j] == 'O' && board[i+1][j] == board[i][j]) {
union(i * n2 + j, (i+1) * n2 + j, parent);
}
}
}
List<Integer> list = new ArrayList<>();
for (int i = 0; i < parent.length; i++) {
int x = i / n2;
int y = i - x * n2;
if (i == parent[i] && board[x][y] == 'O') {
list.add(i);
}
}
for (int i = 0; i < list.size(); i++) {
boolean b = true;
for (int j = 0; j < parent.length; j++) {
int x = j / n2;
int y = j - x * n2;
if (find(j, parent) == list.get(i) && (x == 0 || x == n1 - 1 || y == 0 || y == n2 - 1)) {
b = false;
}
}
if (b) {
for (int j = 0; j < parent.length; j++) {
int x = j / n2;
int y = j - x * n2;
if (find(j, parent) == list.get(i)) {
board[x][y] ='X';
}
}
}
}
}
public int find(int k, int[] parent) {
if (parent[k] != k) {
parent[k] = find(parent[k], parent);
}
return parent[k];
}
public void union(int i, int j, int[] parent) {
int x = find(i, parent);
int y = find(j, parent);
if (x != y) {
parent[x] = y;
}
}
}
|
