Created
December 22, 2019 11:02
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```java | |
public String minimumWindow01(String s, String t) { | |
int l = 0, r = 0, N = s.length() , start = 0, minLen = Integer.MAX_VALUE; | |
Map<Character, Integer> needs = new HashMap(); | |
for (char c : t.toCharArray()) { | |
needs.put(c, needs.getOrDefault(c, 0) + 1); | |
} | |
Map<Character, Integer> windows = new HashMap(); | |
int match = 0; | |
while (r < N) { | |
char c1 = s.charAt(r); | |
if (needs.containsKey(c1)) { | |
windows.put(c1, windows.getOrDefault(c1, 0) + 1); | |
if (windows.get(c1) == needs.get(c1)) { | |
match++; | |
} | |
} | |
r++; | |
// find 可行解, pursue 最优解 | |
while (match == needs.size()) { | |
// update | |
if (r - l < minLen) { | |
start = l; | |
minLen = r - l; | |
} | |
char c2 = s.charAt(l); | |
if (needs.containsKey(c2)) { | |
windows.put(c2, windows.get(c2) - 1); | |
if (windows.get(c2) < needs.get(c2)) { | |
match--; | |
} | |
} | |
l++; | |
} | |
} | |
return minLen == Integer.MAX_VALUE ? "" : s.substring(start, start + minLen); | |
} | |
``` |
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