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S54.java
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S54.java
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package S51_60;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.Set;
/**
* 字符流中第一个不重复的字符
* Created by Elvis on 2019/12/31.
*/
public class S54 {
public static void main(String[] args) {
Insert('g');
System.out.println(FirstAppearingOnce());
Insert('o');
System.out.println(FirstAppearingOnce());
Insert('o');
System.out.println(FirstAppearingOnce());
Insert('g');
System.out.println(FirstAppearingOnce());
Insert('l');
System.out.println(FirstAppearingOnce());
// Iterator<Character> it = set1.iterator();
// while (it.hasNext()) {
// System.out.println(it.next() + "--");
// }
Insert('e');
System.out.println(FirstAppearingOnce());
}
int[] count = new int[256]; // 字符出现的次数
int[] index = new int[256]; // 字符出现的次数
int number = 0;
public void Insert1(char ch) {
count[ch]++;
index[ch] = number++;
}
public char FirstAppearingOnce1() {
int minIndex = number;
char ch = '#';
for (int i = 0; i < 256; i++) {
if (count[i] == 1 && index[i] < minIndex) {
ch = (char) i;
minIndex = index[i];
}
}
return ch;
}
public static Set<Character> set1 = new LinkedHashSet<>();
public static Set<Character> set2 = new HashSet<>();
public static void Insert(char ch) {
if (!set1.contains(ch) && !set2.contains(ch)) {
set1.add(ch);
} else {
set1.remove(ch);
set2.add(ch);
}
}
//return the first appearence once char in current stringstream
public static char FirstAppearingOnce() {
if (set1.isEmpty()) {
return '#';
} else {
char t = set1.iterator().next();
return t;
}
}
}