Shuffle String

给一个string, 和一个index数字, 求按照index后重新排列的string.

class Solution {
   class Pair{
        char c;
        int i;
        Pair(char c, int i) {
            this.c = c;
            this.i = i;
        }
    }
    public String restoreString(String s, int[] indices) {
        StringBuilder sb = new StringBuilder();
        List<Pair> list = new ArrayList<>();
        for(int i = 0; i < indices.length; i++) {
            list.add(new Pair(s.charAt(i), indices[i]));
        }
        Collections.sort(list, (a, b) -> (a.i - b.i));
        for(Pair p : list) {
            sb.append(p.c);
        }
        return sb.toString();
    }
}