Merge pull request #60 from zhongqin0820/master

Fix issue 59: Failed passing 686. Repeated String Match

Author: aQuaYi

Algorithms/0686.repeated-string-match/repeated-string-match.go

@@ -1,15 +1,33 @@
 package problem0686
 
-import "strings"
-
-func repeatedStringMatch(a string, b string) int {
-	times := max(len(b)/len(a), 1)
-
-	if strings.Contains(strings.Repeat(a, times), b) {
-		return times
+func repeatedStringMatch(A string, B string) int {
+	// ref: https://leetcode.com/problems/repeated-string-match/discuss/108084/C%2B%2B-4-lines-O(m-*-n)-or-O(1)-and-KMP-O(m-%2B-n)-or-O(n)
+	n, m := len(A), len(B)
+	prefTable := make([]int, m+1)
+	for sp, pp := 1, 0; sp < m; {
+		if B[pp] == B[sp] {
+			sp++
+			pp++
+			prefTable[sp] = pp
+		} else if pp == 0 {
+			sp++
+			prefTable[sp] = pp
+		} else {
+			pp = prefTable[pp]
+		}
 	}
-	if strings.Contains(strings.Repeat(a, times+1), b) {
-		return times + 1
+
+	for i, j := 0, 0; i < n; i, j = i+max(1, j-prefTable[j]), prefTable[j] {
+		for j < m && A[(i+j)%n] == B[j] {
+			j++
+		}
+		if j == m {
+			if (i+j)%n == 0 {
+				return (i + j) / n
+			} else {
+				return (i+j)/n + 1
+			}
+		}
 	}
 	return -1
 }

Algorithms/0686.repeated-string-match/repeated-string-match_test.go

@@ -79,6 +79,11 @@ var tcs = []struct {
 		2,
 	},
 
+	{
+		"abc",
+		"cabcabca",
+		4,
+	},
 	// 可以有多个 testcase
 }