Combine the previous three versions of wc. Given a list of lines and a mode flag, return the requested count(s) as a string. This is our own simplified interface, not the real wc flags: the real tool combines flags (such as -lw) and pads its columns with spaces.
Function signature:
public String wc(List<String> lines, String mode)
Mode values:
"l"→ line count, as a string."w"→ word count (whitespace-separated tokens), as a string."c"→ character count (lines only, no separating newlines), as a string."all"→lines + "\t" + words + "\t" + chars.
The "c" count is the one from v3 (the sum of the line lengths, no newlines). Any other mode value, for example "x" or "L" (modes are case-sensitive), gives the same result as "all". For an empty list, "l", "w" and "c" give "0" and "all" gives "0<TAB>0<TAB>0". The input is plain ASCII text.
Example:
Input: lines = ["hello", "world"], mode = "all" Output: "2\t2\t10"
2 lines, 2 words (one per line), 10 characters total.
Compute all three counts in a single pass through
lines, then branch on mode with .equals() (NOT ==).
int numLines = lines.size();
int numWords = 0;
int numChars = 0;
for (String line : lines) {
String trimmed = line.trim();
if (!trimmed.isEmpty()) numWords += trimmed.split("\\s+").length;
numChars += line.length();
}
The full solution:
class Solution {
public String wc(List<String> lines, String mode) {
int numLines = lines.size();
int numWords = 0;
int numChars = 0;
for (String line : lines) {
String trimmed = line.trim();
if (!trimmed.isEmpty()) numWords += trimmed.split("\\s+").length;
numChars += line.length();
}
if (mode.equals("l")) return Integer.toString(numLines);
if (mode.equals("w")) return Integer.toString(numWords);
if (mode.equals("c")) return Integer.toString(numChars);
return numLines + "\t" + numWords + "\t" + numChars;
}
}
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