[LeetCode] Problem 942 - DI String Match

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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

No.1

Input: “IDID”

Output: [0,4,1,3,2]

No.2

Input: “III”

Output: [0,1,2,3]

No.3

Input: “DDI”

Output: [3,2,0,1]

Note

1 <= S.length <= 10000
S only contains characters “I” or “D”.

Code

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public int[] diStringMatch(String S) {
    int n = S.length();
    int left = 0;
    int right = n;
    int[] result = new int[n + 1];

    for (int i = 0; i < n; i++) {
        if (S.charAt(i) == 'I')
            result[i] = left++;
        else
            result[i] = right--;
    }
    result[n] = left;

    return result;
}