最短摘要的生成（编程之美）

LeetCode(Minimum Window Substring)

string minWindow(string s,string t)   {  int m=s.size(),n=t.size();  if(m==0)return "";  if(m<n)return "";  vector<int> expected(256,0),appeared(256,0);for(int i=0;i<n;++i)++expected[t[i]];//i指向窗口的开头，j指向窗口的结尾int i=0,cnt=0,minLength=INT_MAX,minIndex=0;  for(int j=0;j<m;++j)  {  if(expected[s[j]]>0)  {  ++appeared[s[j]];  if(appeared[s[j]]<=expected[s[j]])++cnt;  }//找到一个包含t中所有字符的窗口if(cnt==n)  {//i右移while(expected[s[i]]==0||appeared[s[i]]>expected[s[i]]){--appeared[s[i]];++i;}if(j-i+1<minLength)  {  minLength=j-i+1;  minIndex=i;  }  }  }  if(cnt<n)return "";  else return s.substr(minIndex,minLength);  }