LEARNING JOURNAL

function smallestEquivalentString(s1: string, s2: string, baseStr: string): string {
    const aCharCode = "a".charCodeAt(0);

    const abcStr:string[] = Array.from({length: 26}).map((_,i) => String.fromCharCode(i + aCharCode));

    const uF = new UnionFind(abcStr.length);

    for(let i = 0; i < s1.length; i++) {
        const index1 = s1.charCodeAt(i) - aCharCode;
        const index2 = s2.charCodeAt(i) - aCharCode;

        uF.union(index1, index2);
    }
    
    const indexArr:number[] = [];
    for(let i = 0; i < baseStr.length; i++) {
        const root = uF.findRoot(baseStr.charCodeAt(i) - aCharCode);
        indexArr.push(root);
    }

    return indexArr.map(index => abcStr[index]).join("");
};

class UnionFind {
    private roots: number[];

    constructor(n:number) {
        this.roots = Array.from({length: n}).map((_,i) => i);
    }

    public union(index1:number, index2: number) {
        const root1 = this.findRoot(index1);
        const root2 = this.findRoot(index2);

        if(root1 === root2) return;

        if(root1 < root2) {
            this.roots[root2] = root1;
        }
        else {
            this.roots[root1] = root2;
        }

    }

    public findRoot(i: number) {
   

        if(i === this.roots[i]) return i;

        this.roots[i] = this.findRoot(this.roots[i])

        return this.roots[i];
    }
}