990. Satisfiability of Equality Equations

Link

Solution

Key: 2 times parsing, one for '==' another for checking '!='

 public boolean equationsPossible(String[] equations) {
        int[] map = new int[26];
        for(int i = 0; i < 26; i++){
            map[i] = i;
        }
        
        for(String eq : equations){
            
            if(eq.charAt(1) == '='){
                union(map, eq.charAt(0), eq.charAt(3));
            }
        }
        
        for(String eq : equations){
            if(eq.charAt(1) == '!')
            {
                int aRoot = find(map, eq.charAt(0) - 'a');
                int bRoot = find(map, eq.charAt(3) - 'a');
                if(aRoot == bRoot) return false;
            }
            
        }
        return true;
        
    }
    
    public int find(int[] map, int c){
        if(map[c] != c){
            map[c] = find(map, map[c]);
        }
        return map[c];
    }
    
    
    public void union(int[] map, char a, char b){
        
        int aRoot = find(map, a-'a');
        int bRoot = find(map, b-'a');
        map[bRoot] = aRoot;
    }