add solution for id 3

Author: freefcw

leetcode/longest-substring-without-repeating-characters.go

@@ -0,0 +1,34 @@
+package leetcode
+
+func lengthOfLongestSubstring(s string) int {
+	if len(s) == 0 {
+		return 0
+	}
+	flags := make([]bool, 256)
+	maxLen := 1
+	currentStart := 0
+	for i := 0; i < len(s); i++ {
+		key := s[i]
+		if !flags[key] {
+			flags[key] = true
+			continue
+		}
+		if i-currentStart > maxLen {
+			maxLen = i - currentStart
+		}
+		for currentStart < i {
+			if s[currentStart] == s[i] {
+				currentStart++
+				break
+			}
+			key := s[currentStart]
+			flags[key] = false
+			currentStart++
+		}
+	}
+	if len(s)-currentStart > maxLen {
+		maxLen = len(s) - currentStart
+	}
+
+	return maxLen
+}

leetcode/longest-substring-without-repeating-characters_test.go

@@ -0,0 +1,45 @@
+package leetcode
+
+import "testing"
+
+func TestLengthOfLongestSubstring(t *testing.T) {
+	tests := []struct {
+		input  string
+		expect int
+	}{
+		{
+			input:  "aab",
+			expect: 2,
+		}, {
+			input:  "abcabcbb",
+			expect: 3,
+		}, {
+			input:  "bbbbb",
+			expect: 1,
+		}, {
+			input:  "",
+			expect: 0,
+		}, {
+			input:  "a",
+			expect: 1,
+		}, {
+			input:  "azz",
+			expect: 2,
+		}, {
+			input:  "pwwkew",
+			expect: 3,
+		}, {
+			input:  "abcdefg",
+			expect: 7,
+		}, {
+			input:  " ",
+			expect: 1,
+		},
+	}
+	for i, item := range tests {
+		actual := lengthOfLongestSubstring(item.input)
+		if actual != item.expect {
+			t.Fatalf("%d expect %d, actual %d\n", i, item.expect, actual)
+		}
+	}
+}