Problem
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"
, thenA[i] < A[i+1]
- If
S[i] == "D"
, thenA[i] > A[i+1]
Example 1:
Input: "IDID" Output: [0,4,1,3,2]
Example 2:
Input: "III" Output: [0,1,2,3]
Example 3:
Input: "DDI" Output: [3,2,0,1]
Note:
1 <= S.length <= 10000
S
only contains characters"I"
or"D"
.
Solution: Greedy
“I” -> use the smallest possible number
“D” -> use the largest possible number
Time complexity: O(n)
Space complexity: O(n)
C++
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// Author: Huahua, 44 ms class Solution { public: vector<int> diStringMatch(string S) { const int n = S.length(); vector<int> ans; int lo = 0; int hi = n; for (char c : S) { if (c == 'I') ans.push_back(lo++); else ans.push_back(hi--); } ans.push_back(lo); return ans; } }; |
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