Problem

Given a string S and a character C, return an array of integers representing the shortest distance from the character C in the string.

Example 1:

Input: S = “loveleetcode”, C = ‘e’

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

Note:

S string length is in [1, 10000]. C is a single character, and guaranteed to be in string S. All letters in S and C are lowercase.

Pre analysis

Will use heuristic approach using indexOf and lastIndexOf javascript Array prototypal functions. Time Complexity: O(N), where N is the length of S. We scan through the string twice.

Space Complexity: O(N), the size of ans

Another solution

var shortestToChar = function(S, C) {
    const out = [];

    let lastIndex = Number.NEGATIVE_INFINITY;
    let nextIndex = S.indexOf(C);

    S.split("").map((l, i) => {
        if (i === nextIndex) {
            out[i] = 0;
            lastIndex = nextIndex;
            nextIndex = S.indexOf(C, nextIndex + 1)
            if (nextIndex === -1) nextIndex = Number.POSITIVE_INFINITY;
        } else {
            var dist = Math.min(i - lastIndex, nextIndex - i);
            out[i] = dist;
        }
    })

    return out;
};