670. Maximum Swap

Problem:

Given a non-negative integer, you could swap two digits at most once to get the maximum valued number. Return the maximum valued number you could get.

Example 1:

Input: 2736
Output: 7236
Explanation: Swap the number 2 and the number 7.

Example 2:

Input: 9973
Output: 9973
Explanation: No swap.

Note:

1. The given number is in the range [0, 108]

思路：

Solution (C++):

int maximumSwap(int num) {
    if (num < 10)  return num;
    string s = to_string(num);
    int n = s.length();

    for (int i = 0; i < n-1; ++i) {
        char tmp = s[i];
        int index = i;
        for (int j = i+1; j < n; ++j) {
            if (s[j] >= tmp) {
                tmp = s[j];
                index = j;
            }
        }
        if (s[index] != s[i]) {
            swap(s[i], s[index]);
            break;
        }
    }
    return stoi(s);
}

性能：

Runtime: 0 ms  Memory Usage: 6.1 MB

思路：

Solution (C++):

性能：

Runtime: ms  Memory Usage: MB