assert src != null && target != null && src.length > 0 && src.length == target.length; if (src.length == 1 && src[0].length() == 1) { return replaceChar(s, src[0].charAt(0), target[0]);
assert src != null && target != null && src.length > 0 && src.length == target.length; if (src.length == 1 && src[0].length() == 1) { return replaceChar(s, src[0].charAt(0), target[0]);