[LeetCode]#942. DI String Match

Environment: Python 3.7

Key technique: append function

Given a string S that only contains "I" (increase) or "D" (decrease), let N = S.length.

Return any permutation A of [0, 1, ..., N] such that for all i = 0, ..., N-1:

• If S[i] == "I", then A[i] < A[i+1]
• If S[i] == "D", then A[i] > A[i+1]

Example 1:

Input: "IDID"
Output: [0,4,1,3,2]

Analysis:

1. Set low=0 and high is 4 based on S.
2. If S[i] is “I”, add low to ans list and low add 1.
3. If S[i] is “D”, add high to ans list and high decrease 1.
4. The last list you can add low and high are OK.

Solution:

class Solution:
    def diStringMatch(self, S):
        low,high=0,len(S)
        ans=[]
        for i in S:
            if i=="I":
                ans.append(low)
                low+=1
            else:
                ans.append(high)
                high-=1
        return ans +[low]

Submissions:

Reference:

https://leetcode.com/problems/di-string-match/solution/