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StrArrayDemo.java
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197 lines (157 loc) · 4.71 KB
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package strArray;
import sun.nio.ch.FileKey;
import java.lang.reflect.Array;
import java.util.Arrays;
/**
* @author zhongshanhuang
* @company caih
* @email [email protected]
* @create 2019-08-21 16:52
*/
public class StrArrayDemo {
public static void main(String[] args) {
//1，反转字符串
// SwapWords swapWords = new SwapWords();
// System.out.println(swapWords.swapsWords("how are you"));
//2，比较两个字符串是否是相同字符组成
// CompareSam compareSam = new CompareSam();
// System.out.println(compareSam.compareSamBySort("aaaabbc","abcbaaa"));
// System.out.println(compareSam.compareSam("aaaabbc","abcbaa"));
//3,删除重复字符
// RemoveDuplicate removeDuplicate = new RemoveDuplicate();
// System.out.println(removeDuplicate.removeDuplicate("abcaabcd"));
// System.out.println(removeDuplicate.removeDuplicateBySpace("abcaabcd"));
}
}
/**
* 1，反转字符串
*/
class SwapWords {
public String swapsWords(String s) {
char[] cArr = s.toCharArray();
//对整个字符串进行反转
swap(cArr, 0, cArr.length - 1);
int begin = 0;
//对每一个单词进行字符串反转
for (int i = 0; i < cArr.length; i++) { //从1开始是因为最开头是“
if (cArr[i] == ' ') {
swap(cArr, begin, i - 1);
begin = i + 1;
}
}
//对最后一个单词进行反转
swap(cArr, begin, cArr.length - 1);
return new String(cArr);
}
private void swap(char[] cArr, int front, int end) {
while (front < end) {
char temp = cArr[end];
cArr[end] = cArr[front];
cArr[front] = temp;
front++;
end--;
}
}
}
/**
* 2，比较两个字符串是否是相同字符组成
*/
class CompareSam {
//1,排序法
public boolean compareSamBySort(String s1, String s2) {
// byte[] b1 = s1.getBytes();
// byte[] b2 = s2.getBytes();
char[] b1 = s1.toCharArray();
char[] b2 = s2.toCharArray();
Arrays.sort(b1);
Arrays.sort(b2);
s1 = new String(b1);
s2 = new String(b2);
if (s1.equals(s2)) {
return true;
} else {
return false;
}
}
//2,空间法
public boolean compareSam(String s1, String s2) {
byte[] b1 = s1.getBytes();
byte[] b2 = s2.getBytes();
int[] bCnt = new int[256];
//初始化为0
for (int i = 0; i < bCnt.length; i++) {
bCnt[i] = 0;
}
//统计个数，增加
for (int i = 0; i < b1.length; i++) {
bCnt[b1[i] - '0']++;
}
//统计个数，减少
for (int i = 0; i < b2.length; i++) {
bCnt[b1[i] - '0']--;
}
//检验
for (int i = 0; i < bCnt.length; i++) {
if (bCnt[i] != 0) {
return false;
}
}
return true;
}
}
/**
* 3,删除字符串中重复的字符
*/
class RemoveDuplicate {
//1,暴力法
public String removeDuplicate(String str) {
char[] cArr = str.toCharArray();
int len = cArr.length;
for (int i = 0; i < len; i++) {
if (cArr[i] == '\0') { //ASCII码为0，表示一个字符串结束的标志
continue;
}
for (int j = i + 1; j < len; j++) {
if (cArr[i] == '\0') {
continue;
}
if (cArr[i] == cArr[j]) {
cArr[i] = '\0';
}
}
}
//去掉'\0'
int cnt = 0;
for (int i = 0; i < len; i++) {
if (cArr[i] != '\0') {
cArr[cnt++] = cArr[i];
}
}
return new String(cArr, 0, cnt);
}
//2，空间换时间法
public String removeDuplicateBySpace(String str) {
char[] cArr = str.toCharArray();
int len = cArr.length;
int[] flags = new int[8]; //只需要8个32为的bit 的int，8 * 32 = 256 bit
for (int i = 0; i < 8; i++) {
flags[i] = 0;
}
for (int i = 0; i < len; i++) {
int index = (int) (cArr[i] / 32);
int shift = (int) (cArr[i] % 32);
if ((flags[index] & (1 << shift)) != 0) { //???
cArr[i] = '\0';
}
flags[index] |= (1 << shift); //???
}
//去掉'\0'
int cnt = 0;
for (int i = 0; i < len; i++) {
if (cArr[i] != '\0') {
cArr[cnt++] = cArr[i];
}
}
return new String(cArr, 0, cnt);
}
}