670.cpp

// greedy.cpp
class Solution {
public:
  int maximumSwap(int num) {
    string res = to_string(num);
    int index1 = -1, index2;
    for (int i = 0; i < res.size(); ++i) {
      for (int j = res.size() - 1; j > i; --j) {
        if (res[j] > res[i]) {
          if (index1 == -1)
            index1 = i, index2 = j;
          else if (res[index2] < res[j])
            index2 = j;
        }
      }
      if (index1 != -1)
        break;
    }
    if (index1 == -1)
      return num;
    swap(res[index1], res[index2]);
    return stoi(res);
  }
};