并查集 力扣990等式方程的可满足性

class Solution {
    public boolean equationsPossible(String[] equations) {
        UnionFind unionfind=new UnionFind(26);
         for(String s:equations){
             if(s.charAt(1)=='=')
             {
                 int index1=s.charAt(0)-'a';
                 int index2=s.charAt(3)-'a';
                 unionfind.union(index1,index2);
             }
        }
        for(String s:equations){
             if(s.charAt(1)=='!')
             {
                 int index1=s.charAt(0)-'a';
                 int index2=s.charAt(3)-'a';
                 if(unionfind.find(index1)==unionfind.find(index2)){
                     return false;
                 }
             }
        }
        return true;
    }
    private class UnionFind{
        private int[] parent;
        public UnionFind(int n)
        {
            this.parent=new int[n];
            for(int i=0;i<n;i++)
            {
                parent[i]=i;
            }
        }
        public void union(int l1,int l2){
            if(find(l1)==find(l2)) return;
            parent[find(l1)]=find(l2);
        }
        public int find(int x)
        {
            if(parent[x]!=x)
            {
                parent[x]=find(parent[x]);
            }
            return parent[x];
        }

    }
}
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