LeetCode 423. Reconstruct Original Digits from English——学会观察，贪心思路

class Solution(object):
    def originalDigits(self, s):
        """
        :type s: str
        :rtype: str
six, zero, two, eight, four中分别包含唯一字母x, z, w, g, u, 根据z,w,x,g,u的个数就可以知道0,2,6,8,4的个数。对于剩下的one,three,five,seven，one可以由字符o的个数减去在0,2,4,6,8中出现的o的个数。
        """
        char_cnt = [0]*26
        for c in s:
            char_cnt[ord(c)-ord(‘a‘)] += 1
        mapp_digits = {"zero": 0, "one": 1, "two": 2, "three": 3, "four": 4, "five": 5, "six": 6, "seven": 7, "eight": 8, "nine": 9}
        digits_c = {"zero": "z", "two": "w", "four": "u", "six": "x",  "eight": "g"}
        digits_c2 = {"one": "o", "three": "h", "five": "f", "seven": "s"}
        digits_c3 = {"nine": "i"}
        out = []
        for digits in (digits_c, digits_c2, digits_c3):
            for d in digits:
                cnt = char_cnt[ord(digits[d])-ord(‘a‘)]
                if cnt > 0:
                    out += [mapp_digits[d]] * cnt
                    for c in d:
                        char_cnt[ord(c)-ord(‘a‘)] -= cnt
        out.sort()
        return "".join(str(c) for c in out)