[LeetCode] 942. DI String Match (C++)

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[LeetCode] 942. DI String Match (C++)

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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]

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”.

class Solution {
public:
    vector<int> diStringMatch(string S) {
        vector<int> res;
        int i=0; // min
        int j=S.size(); // max
        for(char c:S) {
            if(c=='D') { // decrease
                res.push_back(j--);
            }
            else { // increase
                res.push_back(i++);
            }
        }
        res.push_back(i); // the last element
        return res;
    }
};


/**
 * Submission Detail:
 * Runtime: 40 ms, faster than 99.76% of C++ online submissions for DI String Match.
 * Memory Usage: 10.3 MB, less than 98.79% of C++ online submissions for DI String Match.
 */