821. Shortest Distance to a Character

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] 

Analysis:

2次遍历。

1： 从左往右S里面的字符到C的最短距离。

2： 从右往左S里面的字符到C的最短距离。

distance[i], S.charAt(i) 到C的最短距离。

Solution:

class Solution {
    public int[] shortestToChar(String S, char C) {
        int len = S.length();
        char[] chars = S.toCharArray();
        int[] res = new int[len];
        int pos = Integer.MIN_VALUE/2;
        for (int i = 0; i < len; i++) {
            if (S.charAt(i) == C) pos = i;
            res[i] = i - pos;
        }
        pos = Integer.MAX_VALUE/2;
        for (int i = len - 1; i >= 0; i--) {
            if (S.charAt(i) == C) pos = i;
            res[i] = Math.min(pos - i, res[i]);
        }
        return res;
    }
}