Gives you a string sss , and some "index pairs" arraypairs pairs inthe stringP A I R & lt S , whichpairs[i] = [a, b]represents a string two indexes (numbers from000 start).
You can swap in pairs as many times as you likeThe character at any pair of indices in p a i r s .
Return after several exchanges, sss can become the smallest string lexicographically.
Example 1:
输入：s = "dcab", pairs = [[0,3],[1,2]]
输出："bacd"
解释：
交换 s[0] 和 s[3], s = "bcad"
交换 s[1] 和 s[2], s = "bacd"
Example 2:
输入：s = "dcab", pairs = [[0,3],[1,2],[0,2]]
输出："abcd"
解释：
交换 s[0] 和 s[3], s = "bcad"
交换 s[0] 和 s[2], s = "acbd"
交换 s[1] 和 s[2], s = "abcd"
Example 3:
输入：s = "cba", pairs = [[0,1],[1,2]]
输出："abc"
解释：
交换 s[0] 和 s[1], s = "bca"
交换 s[1] 和 s[2], s = "bac"
交换 s[0] 和 s[1], s = "abc"
prompt:
1 < = s . l e n g t h < = 1 0 5 1 <= s.length <= 10^5 1<=s.length<=105
0 < = p a i r s . l e n g t h < = 1 0 5 0 <= pairs.length <= 10^5 0<=pairs.length<=105
0 < = p a i r s [ i ] [ 0 ] , p a i r s [ i ] [ 1 ] < s . l e n g t h 0 <= pairs[i][0], pairs[i][1] < s.length 0<=pairs[i][0],pairs[i][1]<s.length
s s s contains only lowercase English letters
class Solution {
public:
int f[100010];
int find(int x){
return x==f[x]?x:f[x]=find(f[x]);
}
string smallestStringWithSwaps(string s, vector<vector<int>>& pairs) {
int n=s.length();
for (int i=0;i<n;i++){
f[i]=i;
}
for (auto &it :pairs){
int x=find(it[0]);
int y=find(it[1]);
f[x]=y;
}
unordered_map<int,vector<int> >ma;
for (int i=0;i<n;i++){
ma[find(i)].push_back(s[i]);
}
for (auto &[x,vec] :ma){
sort(vec.begin(),vec.end(),greater<int>());
}
for (int i=0;i<n;i++){
int x=find(i);
s[i]=ma[x].back();
ma[x].pop_back();
}
return s;
}
};