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| class Solution {
private static class UnionFind {
private final int[] parent;
public UnionFind(int count) {
this.parent = new int[count];
for (int i = 0; i < count; i++) {
this.parent[i] = i;
}
}
public void union(int x, int y) {
int xRoot = getRoot(x);
int yRoot = getRoot(y);
if (xRoot == yRoot) {
return;
}
parent[xRoot] = yRoot;
}
public int getRoot(int x) {
while (x != parent[x]) {
parent[x] = parent[parent[x]];
x = parent[x];
}
return x;
}
public boolean isConnected(int x, int y) {
return getRoot(x) == getRoot(y);
}
}
public boolean equationsPossible(String[] equations) {
UnionFind unionFind = new UnionFind(26);
for (String equation : equations) {
if (equation.charAt(1) == '=') {
int x = equation.charAt(0) - 'a';
int y = equation.charAt(3) - 'a';
unionFind.union(x, y);
}
}
for (String equation : equations) {
if (equation.charAt(1) == '!') {
int x = equation.charAt(0) - 'a';
int y = equation.charAt(3) - 'a';
if (unionFind.isConnected(x, y)) {
return false;
}
}
}
return true;
}
}
|
References
990. Satisfiability of Equality Equations
使用并查集处理不相交集合问题（Java、Python）