@@ -288,4 +288,230 @@ impl Solution {
288288
289289<!-- solution:end -->
290290
291+ <!-- solution:start -->
292+
293+ ### 方法二：枚举 + KMP
294+
295+ 我们可以使用 KMP 算法来优化字符串的合并过程。
296+
297+ 时间复杂度 $O(n)$，空间复杂度 $O(n)$。其中 $n$ 是三个字符串的长度之和。
298+
299+ <!-- tabs:start -->
300+
301+ #### Python3
302+
303+ ``` python
304+ class Solution :
305+ def minimumString (self a : str , b : str , c : str ) -> str :
306+ def f (s : str , t : str ) -> str :
307+ if s in t:
308+ return t
309+ if t in s:
310+ return s
311+ p = t + " #" + s + " $"
312+ n = len (p)
313+ next = [0 ] * n
314+ next [0 ] = - 1
315+ i, j = 2 , 0
316+ while i < n:
317+ if p[i - 1 ] == p[j]:
318+ j += 1
319+ next [i] = j
320+ i += 1
321+ elif j:
322+ j = next [j]
323+ else :
324+ next [i] = 0
325+ i += 1
326+ return s + t[next [- 1 ] :]
327+
328+ ans = " "
329+ for a, b, c in permutations((a, b, c)):
330+ s = f(f(a, b), c)
331+ if ans == " " or len (s) < len (ans) or (len (s) == len (ans) and s < ans):
332+ ans = s
333+ return ans
334+ ```
335+
336+ #### Java
337+
338+ ``` java
339+ class Solution {
340+ public String minimumString (String a , String b , String c ) {
341+ String [] s = {a, b, c};
342+ int [][] perm = {{0 , 1 , 2 }, {0 , 2 , 1 }, {1 , 0 , 2 }, {1 , 2 , 0 }, {2 , 1 , 0 }, {2 , 0 , 1 }};
343+ String ans = " "
344+ for (var p : perm) {
345+ int i = p[0 ], j = p[1 ], k = p[2 ];
346+ String t = f(f(s[i], s[j]), s[k]);
347+ if (" " . equals(ans) || t. length() < ans. length()
348+ || (t. length() == ans. length() && t. compareTo(ans) < 0 )) {
349+ ans = t;
350+ }
351+ }
352+ return ans;
353+ }
354+
355+ private String f (String s , String t ) {
356+ if (s. contains(t)) {
357+ return s;
358+ }
359+ if (t. contains(s)) {
360+ return t;
361+ }
362+ char [] p = (t + " #" + s + " $" . toCharArray();
363+ int n = p. length;
364+ int [] next = new int [n];
365+ next[0 ] = - 1 ;
366+ for (int i = 2 , j = 0 ; i < n;) {
367+ if (p[i - 1 ] == p[j]) {
368+ next[i++ ] = ++ j;
369+ } else if (j > 0 ) {
370+ j = next[j];
371+ } else {
372+ next[i++ ] = 0 ;
373+ }
374+ }
375+ return s + t. substring(next[n - 1 ]);
376+ }
377+ }
378+ ```
379+
380+ #### C++
381+
382+ ``` cpp
383+ class Solution {
384+ public:
385+ string minimumString(string a, string b, string c) {
386+ vector<string > s = {a, b, c};
387+ vector<vector<int >> perm = {{0, 1, 2}, {0, 2, 1}, {1, 0, 2}, {1, 2, 0}, {2, 1, 0}, {2, 0, 1}};
388+ string ans = "";
389+ for (auto& p : perm) {
390+ int i = p[ 0] , j = p[ 1] , k = p[ 2] ;
391+ string t = f(f(s[ i] , s[ j] ), s[ k] );
392+ if (ans == "" || t.size() < ans.size() || (t.size() == ans.size() && t < ans)) {
393+ ans = t;
394+ }
395+ }
396+ return ans;
397+ }
398+
399+ string f(string s, string t) {
400+ if (s.find(t) != string::npos) {
401+ return s;
402+ }
403+ if (t.find(s) != string::npos) {
404+ return t;
405+ }
406+ string p = t + "#" + s + "$";
407+ int n = p.size();
408+ int next[n];
409+ next[0] = -1;
410+ next[1] = 0;
411+ for (int i = 2, j = 0; i < n;) {
412+ if (p[i - 1] == p[j]) {
413+ next[i++] = ++j;
414+ } else if (j > 0) {
415+ j = next[j];
416+ } else {
417+ next[i++] = 0;
418+ }
419+ }
420+ return s + t.substr(next[n - 1]);
421+ };
422+ };
423+ ```
424+
425+ #### Go
426+
427+ ``` go
428+ func minimumString (a string , b string , c string ) string {
429+ f := func (s, t string ) string {
430+ if strings.Contains (s, t) {
431+ return s
432+ }
433+ if strings.Contains (t, s) {
434+ return t
435+ }
436+ p := t + " #" " $"
437+ n := len (p)
438+ next := make ([]int , n)
439+ next[0 ] = -1
440+ for i , j := 2 , 0 ; i < n; {
441+ if p[i-1 ] == p[j] {
442+ j++
443+ next[i] = j
444+ i++
445+ } else if j > 0 {
446+ j = next[j]
447+ } else {
448+ next[i] = 0
449+ i++
450+ }
451+ }
452+ return s + t[next[n-1 ]:]
453+ }
454+ s := [3 ]string {a, b, c}
455+ ans := " "
456+ for _ , p := range [][]int {{0 , 1 , 2 }, {0 , 2 , 1 }, {1 , 0 , 2 }, {1 , 2 , 0 }, {2 , 0 , 1 }, {2 , 1 , 0 }} {
457+ i , j , k := p[0 ], p[1 ], p[2 ]
458+ t := f (f (s[i], s[j]), s[k])
459+ if ans == " " len (t) < len (ans) || (len (t) == len (ans) && t < ans) {
460+ ans = t
461+ }
462+ }
463+ return ans
464+ }
465+ ```
466+
467+ #### TypeScript
468+
469+ ``` ts
470+ function minimumString(a : string , b : string , c : string ): string {
471+ const = (s : string , t : string ): string => {
472+ if (s .includes (t )) {
473+ return s ;
474+ }
475+ if (t .includes (s )) {
476+ return t ;
477+ }
478+ const = t + ' #' + s + ' $'
479+ const = p .length ;
480+ const : number [] = Array (n ).fill (0 );
481+ next [0 ] = - 1 ;
482+ for (let i = 2 , j = 0 ; i < n ; ) {
483+ if (p [i - 1 ] === p [j ]) {
484+ next [i ++ ] = ++ j ;
485+ } else if (j ) {
486+ j = next [j ];
487+ } else {
488+ next [i ++ ] = 0 ;
489+ }
490+ }
491+ return s + t .slice (next [n - 1 ]);
492+ };
493+ const : string [] = [a , b , c ];
494+ const : number [][] = [
495+ [0 , 1 , 2 ],
496+ [0 , 2 , 1 ],
497+ [1 , 0 , 2 ],
498+ [1 , 2 , 0 ],
499+ [2 , 0 , 1 ],
500+ [2 , 1 , 0 ],
501+ ];
502+ let ans = ' '
503+ for (const of perm ) {
504+ const = f (f (s [i ], s [j ]), s [k ]);
505+ if (ans === ' ' || t .length < ans .length || (t .length === ans .length && t < ans )) {
506+ ans = t ;
507+ }
508+ }
509+ return ans ;
510+ }
511+ ```
512+
513+ <!-- tabs:end -->
514+
515+ <!-- solution:end -->
516+
291517<!-- problem:end -->
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