Build a more powerful version of the Unix tr command. Given a list of lines and two equal-length strings set1 and set2, replace every character in each line that appears in set1 at index i with set2[i]. Characters not in set1 are unchanged. Return the lines joined by newline characters (\n).
Notes: set1 and set2 have the same length, contain only ASCII characters, and set1 has no repeated character. Characters are taken literally: there are no ranges like a-z. All replacements happen at once, so set1 = "ab", set2 = "ba" swaps the two letters. Lines may be empty.
Function signature:
tr(lines: string[], set1: string, set2: string): string
Example:
Input: lines = ["banana", "cherry"], set1 = "abc", set2 = "ABC" Output: "BAnAnA\nCherry" When printed: BAnAnA Cherry
Build a
Map from each char of set1 to the same-index char of set2. Then walk every line and replace each char via the map (or pass it through unchanged).
let map = new Map<string, string>();
for (let i = 0; i < set1.length; i++) {
map.set(set1[i], set2[i]);
}
// per char: map.has(ch) ? map.get(ch) : ch
The full solution:
class Solution {
tr(lines: string[], set1: string, set2: string): string {
let map = new Map<string, string>();
for (let i = 0; i < set1.length; i++) {
map.set(set1[i], set2[i]);
}
let result: string[] = [];
for (let i = 0; i < lines.length; i++) {
let out = "";
for (let j = 0; j < lines[i].length; j++) {
let ch = lines[i][j];
out += map.has(ch) ? map.get(ch) : ch;
}
result.push(out);
}
return result.join("\n");
}
}
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