Add Solution 0003 [golang]

Author: lightfish-zhang

solution/0003.Longest Substring Without Repeating Characters/Solution.go

@@ -0,0 +1,22 @@
+/*
+ * Report by leetcode.com
+ * Runtime: 8 ms, Memory Usage: 3.2 MB
+ */
+func lengthOfLongestSubstring(s string) int {
+	mathMax := func(a, b int) int {
+		if a > b {
+			return a
+		}
+		return b
+	}
+	cache := map[rune]int{}
+	var max, position int
+	for i, r := range s {
+		if num, ok := cache[r]; ok {
+			position = mathMax(position, num+1)
+		}
+		cache[r] = i
+		max = mathMax(max, i-position+1)
+	}
+	return max
+}