Given a string S and a string T, find the minimum window in S which will contain all the characters in T in complexity O(n).
For example,
S = "ADOBECODEBANC"
T = "ABC"
Minimum window is "BANC".
Note:
If there is no such window in S that covers all characters in T, return the emtpy string "".
If there are multiple such windows, you are guaranteed that there will always be only one unique minimum window in S.
public class Solution { public String minWindow(String S, String T) { // Start typing your Java solution below // DO NOT write main() function if (S == null || T == null || S.length() == 0 || T.length() == 0) { return ""; } int[] needToFind = new int[256]; int[] hasFound = new int[256]; for (int i = 0; i < T.length(); i++) { needToFind[T.charAt(i)]++; } int minWinLen = Integer.MAX_VALUE; int count = 0, tLen = T.length(); int winBeg = 0, winEnd = 0; for (int begin = 0, end = 0; end < S.length(); end++) { if (needToFind[S.charAt(end)] == 0) { continue; } hasFound[S.charAt(end)]++; if(hasFound[S.charAt(end)] <= needToFind[S.charAt(end)]){ count ++; } if(count == tLen){ while(needToFind[S.charAt(begin)] == 0 || hasFound[S.charAt(begin)] > needToFind[S.charAt(begin)]){ if(hasFound[S.charAt(begin)] > needToFind[S.charAt(begin)]){ hasFound[S.charAt(begin)]--; } begin ++; } int winLen = end - begin + 1; if(winLen < minWinLen){ winBeg = begin; winEnd = end; minWinLen = winLen; } } } if (count == T.length()) { return S.substring(winBeg, winEnd + 1); } return ""; } }
ublic class Solution { public String minWindow(String S, String T) { // Start typing your Java solution below // DO NOT write main() function if (S == null || T == null || S.length() == 0 || T.length() == 0) { return ""; } HashMap<Character, Integer> map = new HashMap<Character, Integer>(); for(int i = 0 ; i < T.length() ; i++){ if(map.containsKey(T.charAt(i))){ map.put(T.charAt(i), map.get(T.charAt(i))+1); } else{ map.put(T.charAt(i), 1); } } int count = 0; int pre = 0; String result = ""; int minLen = S.length() + 1; for(int i = 0 ; i < S.length() ; i++ ){ if(map.containsKey(S.charAt(i))){ map.put(S.charAt(i),map.get(S.charAt(i))-1); if(map.get(S.charAt(i)) >=0) count++; while(count == T.length()){ if(map.containsKey(S.charAt(pre))){ map.put(S.charAt(pre),map.get(S.charAt(pre))+1); if(map.get(S.charAt(pre))>0) { if(minLen > i-pre +1){ result = S.substring(pre,i + 1); minLen = i - pre + 1; } count--; } } pre++; } } } return result; } }