常规解法，空间复杂度时间复杂度O(n)

class Solution {
public:
    string restoreString(string s, vector<int>& indices) {
        string res(s);
        int n = s.size();
        for(int i = 0;i < n;i++)
        {
            res[indices[i]] = s[i];
        }
        
        return res;
    }
};

运行结果：

Runtime: 8 ms, faster than 98.74% of C++ online submissions for Shuffle String.
Memory Usage: 15.5 MB, less than 20.67% of C++ online submissions for Shuffle String.

空间复杂度O(1) 时间复杂度O(n)解法：

class Solution {
public:
    string restoreString(string s, vector<int>& indices) {
        int n = s.size();
        for(int i = 0;i < n;i++)
        {
            while(indices[i] != i)
            {
                swap(s[i],s[indices[i]]);
                swap(indices[i],indices[indices[i]]);
            }
        }
        
        return s;
    }
};

运行结果：

Runtime: 16 ms, faster than 66.25% of C++ online submissions for Shuffle String.
Memory Usage: 15.4 MB, less than 43.20% of C++ online submissions for Shuffle String.