LeetCode Online Judge 题目C# 练习 - Substring with Concatenation of All Words

You are given a string, S, and a list of words, L, that are all of the same length. Find all starting indices of substring(s) in S that is a concatenation of each word in L exactly once and without any intervening characters.
For example, given:
S: "barfoothefoobarman"
L: ["foo", "bar"]

You should return the indices: [0,9].
(order does not matter).

 1         public static List<int> SubstringwithConcatenationofAllWords(string S, List<string> L)
 2         {
 3             List<int> ret = new List<int>();
 4             Dictionary<string, int> map_count = new Dictionary<string, int>();
 5             Dictionary<string, int> map_found = new Dictionary<string, int>();
 6             int l = L[0].Length;
 7             int total = L.Count;
 8 
 9             //Add words in L to the map_count
10             for (int i = 0; i < total; i++)
11             {
12                 if (map_count.ContainsKey(L[i]))
13                     map_count[L[i]]++;
14                 else
15                     map_count.Add(L[i], 1);
16             }
17 
18             //last index need to check
19             int last = S.Length - l * total;
20             for (int i = 0; i <= last; i++)
21             {
22                 int index = i;
23                 string sub = S.Substring(index, l);
24                 for(int j = 0; j < total; j++)
25                 {
26                     if (!map_count.ContainsKey(sub))
27                         break;
28                     else if (map_found.ContainsKey(sub) && map_found[sub] >= map_count[sub])
29                         break;
30                     else
31                     {
32                         if (map_found.ContainsKey(sub))
33                             map_found[sub]++;
34                         else
35                             map_found.Add(sub, 1);
36                         index += l;
37                         sub = S.Substring(index, l);
38                     }
39 
40                     if (j == total - 1)
41                     {
42                         ret.Add(i);
43                     }
44                 }
45 
46                 map_found.Clear();
47             }
48 
49             return ret;
50         }

代码分析：

　　这个代码过不了大数据，Time Limit Exceeded。 可能是SubString这个方法比较耗性能。

　　这个是别人用JAVA做的，能过大数据，先往下复习，回头再看 http://heartfire.cc/wp/substring-with-concatenation-of-all-words/ 

posted @ 2012-10-18 23:56  ETCOW  阅读(491)  评论(0)  编辑  收藏  举报