LeetCode 670. Maximum Swap 字符串有坑

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]

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 從前向後，從大到小，找比自己大的字符，如果找到了，把最靠後的位和當前位交換：

class Solution(object):
    def maximumSwap(self, num):
        A = list(str(num))
        last = {x: i for i, x in enumerate(A)}
        print(last)
        for i in range(len(A)):
            for d in sorted(last.keys(), reverse=True):
                if last[d] > i and d>A[i]:
                    A[i], A[last[d]] = A[last[d]], A[i]
                    return int("".join(A))
        return num