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1528. Shuffle String.md

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1528. Shuffle String

1. Description

Given a string s and an integer array indices of the same length.

The string s will be shuffled such that the character at the $i^{\text{th}}$ position moves to indices[i] in the shuffled string.

Return the shuffled string.

Example 1:

Input: s = "codeleet", indices = [4,5,6,7,0,2,1,3]
Output: "leetcode"
Explanation: As shown, "codeleet" becomes "leetcode" after shuffling.

Example 2:

Input: s = "abc", indices = [0,1,2]
Output: "abc"
Explanation: After shuffling, each character remains in its position.

Example 3:

Input: s = "aiohn", indices = [3,1,4,2,0]
Output: "nihao"

Example 4:

Input: s = "aaiougrt", indices = [4,0,2,6,7,3,1,5]
Output: "arigatou"

Example 5:

Input: s = "art", indices = [1,0,2]
Output: "rat"

Constraints:

  • s.length == indices.length == n
  • 1 <= n <= 100
  • s contains only lower-case English letters.
  • 0 <= indices[i] < n
  • All values of indices are unique (i.e. indices is a permutation of the integers from 0 to n - 1).

2. Solutions

Solution 1: Language: C Malloc a New String and Copying

Malloc a string called new which has the same size as the given one, and we could copy each char from s to new by the correct order. The size should be (indicesSize + 1), Because the string s should be ['c','o','d','e','l','e','e','t','\0'].

Be aware that new[indices[i]] = s[i]; is tried to put each char in s to the correct place; but new[i] = s[indices[i]]; is tried to sort the original string by the indices order. They are totally different, and the first one could only return the excepted result.

  • Thursday, 29 April, 2021
  • Time Complexity: $O(n)$
  • Space Complexity: $O(n)$
  • Runtime: 4 ms, faster than 86.13% of C online submissions for Shuffle String.
  • Memory Usage: 6 MB, less than 70.65% of C online submissions for Shuffle String.
// If the function free() needs to be called?
char *restoreString(char *s, int *indices, int indicesSize) {
    char *new = malloc((indicesSize + 1) * sizeof(char));
    for (int i = 0; i < indicesSize; i++) {
        new[indices[i]] = s[i];
    }
    // And string should end with a '\0'.
    new[indicesSize] = '\0';
    return new;
}