03-Longest-Substring-Without-Repeating-Characters initial

Author: mzeeshan138

03-Longest-Substring-Without-Repeating-Characters.js

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+/**
+ * @param {string} s
+ * @return {number}
+ */
+var lengthOfLongestSubstring = function (s) {
+  const lastIndex = new Map();
+  let maxLen = 0;
+  let i = 0;
+
+  for (let j = 0; j < s.length; j++) {
+    const ch = s[j];
+    if (lastIndex.has(ch) && lastIndex.get(ch) >= i) {
+      i = lastIndex.get(ch) + 1;
+    }
+    lastIndex.set(ch, j);
+    maxLen = Math.max(maxLen, j - i + 1);
+  }
+
+  return maxLen;
+};