Method increaseRank

javascript/0684-redundant-connection.js:84–86

(head, tail, { rank } = this)

    }

    increaseRank(head, tail, { rank } = this) {
        rank[head] += rank[tail];
    }

    union(src, dst, { rank } = this) {
        const [rootSrc, rootDst] = [this.find(src), this.find(dst)];