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72 lines
1.3 KiB
Go
72 lines
1.3 KiB
Go
package leetcode
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// 解法一 位图
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func lengthOfLongestSubstring(s string) int {
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if len(s) == 0 {
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return 0
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}
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var bitSet [256]bool
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result, left, right := 0, 0, 0
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for left < len(s) {
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// 右侧字符对应的 bitSet 被标记 true，说明此字符在 X 位置重复，需要左侧向前移动，直到将 X 标记为 false
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if bitSet[s[right]] {
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bitSet[s[left]] = false
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left++
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} else {
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bitSet[s[right]] = true
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right++
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}
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if result < right-left {
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result = right - left
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}
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if left+result >= len(s) || right >= len(s) {
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break
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}
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}
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return result
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}
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// 解法二 滑动窗口
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func lengthOfLongestSubstring1(s string) int {
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if len(s) == 0 {
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return 0
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}
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var freq [127]int
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result, left, right := 0, 0, -1
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for left < len(s) {
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if right+1 < len(s) && freq[s[right+1]] == 0 {
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freq[s[right+1]]++
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right++
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} else {
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freq[s[left]]--
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left++
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}
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result = max(result, right-left+1)
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}
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return result
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}
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// 解法三 滑动窗口-哈希桶
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func lengthOfLongestSubstring2(s string) int {
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right, left, res := 0, 0, 0
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indexes := make(map[byte]int, len(s))
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for left < len(s) {
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if idx, ok := indexes[s[left]]; ok && idx >= right {
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right = idx + 1
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}
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indexes[s[left]] = left
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left++
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res = max(res, left-right)
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}
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return res
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}
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func max(a int, b int) int {
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if a > b {
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return a
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}
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return b
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}
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