3. Longest Substring Without Repeating Characters

Author: HC-kang

longest-substring-without-repeating-characters/HC-kang.ts

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+/**
+ * https://leetcode.com/problems/longest-substring-without-repeating-characters
+ * T.C. O(n^2)
+ * S.C. O(n)
+ */
+// function lengthOfLongestSubstring(s: string): number {
+//   let max = 0;
+//   for (let i = 0; i < s.length; i++) {
+//     const SET = new Set();
+//     let count = 0;
+//     for (let j = i; j < s.length; j++) {
+//       if (SET.has(s[j])) break;
+//       SET.add(s[j]);
+//       count += 1;
+//       max = Math.max(max, count);
+//     }
+//   }
+//   return max;
+// }
+
+/**
+ * T.C. O(n)
+ * S.C. O(n)
+ */
+// function lengthOfLongestSubstring(s: string): number {
+//   let left = 0;
+//   let right = 0;
+//   let max = 0;
+//   const SET = new Set();
+
+//   while (s[right]) {
+//     if (SET.has(s[right])) {
+//       SET.delete(s[left]);
+//       left++;
+//     } else {
+//       SET.add(s[right]);
+//       max = Math.max(SET.size, max);
+//       right++;
+//     }
+//   }
+
+//   return max;
+// }
+
+/**
+ * T.C. O(n)
+ * S.C. O(n)
+ */
+function lengthOfLongestSubstring(s: string): number {
+  let left = 0;
+  let right = 0;
+  let max = 0;
+  const MAP = new Map<string, number>();
+
+  while (right < s.length) {
+    if (MAP.has(s[right])) {
+      left = Math.max(MAP.get(s[right])! + 1, left);
+    }
+    MAP.set(s[right], right);
+    max = Math.max(max, right - left + 1);
+    right++;
+  }
+
+  return max;
+}