[Leetcode] Minimum Window Substring
算法思想: http://www.cnblogs.com/lichen782/p/leetcode_minimum_window_substring_3.html
1 public class Solution { 2 public String minWindow(String S, String T) { 3 int N = S.length(); 4 int M = T.length(); 5 if(N < M) 6 return ""; 7 int[] need=new int[256]; 8 int[] find=new int[256]; 9 for(int i=0;i<M;++i) 10 need[T.charAt(i)]++; 11 12 int count=0; 13 int resStart=-1; 14 int resEnd=N; 15 16 for(int start=0,end=0;end<N;++end){ 17 if(need[S.charAt(end)]==0) 18 continue; 19 if(find[S.charAt(end)]<need[S.charAt(end)]) 20 count++; 21 find[S.charAt(end)]++; 22 if(count!=M) 23 continue; 24 25 for(;start<end;++start){ 26 if(need[S.charAt(start)]==0) 27 continue; 28 if(find[S.charAt(start)]<=need[S.charAt(start)]) 29 break; 30 find[S.charAt(start)]--; 31 } 32 if(end-start<resEnd-resStart){ 33 resStart=start; 34 resEnd=end; 35 } 36 } 37 return (resStart==-1)?"":S.substring(resStart, resEnd+1); 38 } 39 }