Leetcode-5199 Smallest String With Swaps(交换字符串中的元素)

#define _for(i,a,b) for(int i = (a);i < b;i ++)
#define _rep(i,a,b) for(int i = (a);i > b;i --)
#define INF 0x3f3f3f3f
#define MOD 1000000007
#define pb push_back
#define maxn 100003

int par[maxn]; //父亲
int high[maxn]; //树的高度

void init(int n)
{
    _for(i,0,n)
    {
        par[i] = i;
        high[i] = 0;
    }
}

int find(int x)
{
    return par[x] == x ? x : par[x] = find(par[x]);
}

void unite(int x,int y)
{
    x = find(x);
    y = find(y);
    if(x==y) return ;

    if(high[x]<high[y])
        par[x] = y;
    else
    {
        par[y] = x;
        if(high[x]==high[y])
            high[x] ++;
    }
}

bool same(int x,int y)
{
    return find(x) == find(y);
}

class Solution
{
    vector<int> a[maxn];
    public:
        string smallestStringWithSwaps(string s, vector<vector<int>>& pairs)
        {
            int n = s.size();
            string rnt = s;
            init(n);
            _for(i,0,pairs.size())
                unite(pairs[i][0],pairs[i][1]);
            
            _for(i,0,s.size())
                a[find(i)].pb(i);
            
            _for(i,0,n)
            {
                string tmp;
                _for(j,0,a[i].size())
                    tmp += s[a[i][j]];
                sort(tmp.begin(),tmp.end());
                _for(j,0,a[i].size())
                    rnt[a[i][j]] = tmp[j];
            }
            return rnt;
        }
};