Longest Substring with at most K Distinct characters

Author: valmsmith39a

src/Review_2024/LongestSubstringWKDistinctChars.java

@@ -0,0 +1,40 @@
+package Review_2024;
+
+import java.util.Map;
+import java.util.HashMap;
+
+public class LongestSubstringWKDistinctChars {
+
+	public int longestSubstringWKDistinctChars(String s, int k) {
+		if (s == null || s.length() == 0 || k == 0) {
+			return 0;
+		}
+
+		Map<Character, Integer> charMap = new HashMap<>();
+		int left = 0;
+		int maxLen = 0;
+
+		for (int right = 0; right < s.length(); right++) {
+			char c = s.charAt(right);
+			charMap.put(c, right);
+
+			while (charMap.size() > k) {
+				char lc = s.charAt(left);
+				if (charMap.get(lc) == left) {
+					charMap.remove(lc);
+				}
+				left++;
+			}
+			maxLen = Math.max(maxLen, right - left + 1);
+		}
+		return maxLen;
+	}
+
+	public static void main(String[] args) {
+		LongestSubstringWKDistinctChars ls = new LongestSubstringWKDistinctChars();
+		String s = "eceba";
+		int k = 2;
+		int len = ls.longestSubstringWKDistinctChars(s, k);
+		System.out.println(len);
+	}
+}