diff --git a/problems/0028.实现strStr.md b/problems/0028.实现strStr.md index 634d8535..d67e5f70 100644 --- a/problems/0028.实现strStr.md +++ b/problems/0028.实现strStr.md @@ -1059,5 +1059,112 @@ func getNext(_ next: inout [Int], needle: [Character]) { ``` +> 前缀表右移 + +```swift +func strStr(_ haystack: String, _ needle: String) -> Int { + + let s = Array(haystack), p = Array(needle) + guard p.count != 0 else { return 0 } + + var j = 0 + var next = [Int].init(repeating: 0, count: p.count) + getNext(&next, p) + + for i in 0 ..< s.count { + + while j > 0 && s[i] != p[j] { + j = next[j] + } + + if s[i] == p[j] { + j += 1 + } + + if j == p.count { + return i - p.count + 1 + } + } + + return -1 + } + + // 前缀表后移一位,首位用 -1 填充 + func getNext(_ next: inout [Int], _ needle: [Character]) { + + guard needle.count > 1 else { return } + + var j = 0 + next[0] = j + + for i in 1 ..< needle.count-1 { + + while j > 0 && needle[i] != needle[j] { + j = next[j-1] + } + + if needle[i] == needle[j] { + j += 1 + } + + next[i] = j + } + next.removeLast() + next.insert(-1, at: 0) + } +``` + +> 前缀表统一不减一 +```swift + +func strStr(_ haystack: String, _ needle: String) -> Int { + + let s = Array(haystack), p = Array(needle) + guard p.count != 0 else { return 0 } + + var j = 0 + var next = [Int](repeating: 0, count: needle.count) + // KMP + getNext(&next, needle: p) + + for i in 0 ..< s.count { + while j > 0 && s[i] != p[j] { + j = next[j-1] + } + + if s[i] == p[j] { + j += 1 + } + + if j == p.count { + return i - p.count + 1 + } + } + return -1 + } + + //前缀表 + func getNext(_ next: inout [Int], needle: [Character]) { + + var j = 0 + next[0] = j + + for i in 1 ..< needle.count { + + while j>0 && needle[i] != needle[j] { + j = next[j-1] + } + + if needle[i] == needle[j] { + j += 1 + } + + next[i] = j + + } + } + +``` + -----------------------
diff --git a/problems/0332.重新安排行程.md b/problems/0332.重新安排行程.md index f7ef8cf7..c71b2a93 100644 --- a/problems/0332.重新安排行程.md +++ b/problems/0332.重新安排行程.md @@ -342,7 +342,7 @@ class Solution: return path ``` -### Go +### GO ```go type pair struct { target string diff --git a/problems/0459.重复的子字符串.md b/problems/0459.重复的子字符串.md index ccfb485c..a51c68ee 100644 --- a/problems/0459.重复的子字符串.md +++ b/problems/0459.重复的子字符串.md @@ -421,5 +421,89 @@ function repeatedSubstringPattern(s: string): boolean { }; ``` + +Swift: + +> 前缀表统一减一 +```swift + func repeatedSubstringPattern(_ s: String) -> Bool { + + let sArr = Array(s) + let len = s.count + if len == 0 { + return false + } + var next = Array.init(repeating: -1, count: len) + + getNext(&next,sArr) + + if next.last != -1 && len % (len - (next[len-1] + 1)) == 0{ + return true + } + + return false + } + + func getNext(_ next: inout [Int], _ str:[Character]) { + + var j = -1 + next[0] = j + + for i in 1 ..< str.count { + + while j >= 0 && str[j+1] != str[i] { + j = next[j] + } + + if str[i] == str[j+1] { + j += 1 + } + + next[i] = j + } + } +``` + +> 前缀表统一不减一 +```swift + func repeatedSubstringPattern(_ s: String) -> Bool { + + let sArr = Array(s) + let len = sArr.count + if len == 0 { + return false + } + + var next = Array.init(repeating: 0, count: len) + getNext(&next, sArr) + + if next[len-1] != 0 && len % (len - next[len-1]) == 0 { + return true + } + + return false + } + + // 前缀表不减一 + func getNext(_ next: inout [Int], _ sArr:[Character]) { + + var j = 0 + next[0] = 0 + + for i in 1 ..< sArr.count { + + while j > 0 && sArr[i] != sArr[j] { + j = next[j-1] + } + + if sArr[i] == sArr[j] { + j += 1 + } + + next[i] = j + } + } +``` + -----------------------