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131 lines
3.3 KiB
131 lines
3.3 KiB
---
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字符串相关
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---
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[05. 替换空格](https://leetcode-cn.com/problems/ti-huan-kong-ge-lcof/)
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```java
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class Solution {
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public String replaceSpace(String s) {
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StringBuilder builder = new StringBuilder();
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int i = 0;
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while (i < s.length()) {
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char c = s.charAt(i);
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if (c == ' ') {
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builder.append("%20");
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} else {
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builder.append(c);
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}
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i++;
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}
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return builder.toString();
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}
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}
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```
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[50. 第一个只出现一次的字符](https://leetcode-cn.com/problems/di-yi-ge-zhi-chu-xian-yi-ci-de-zi-fu-lcof/)
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```java
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class Solution {
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public char firstUniqChar(String s) {
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if (s.length() == 0) {
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return ' ';
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}
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LinkedHashMap<Character, Integer> map = new LinkedHashMap<>();
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for (char c : s.toCharArray()) {
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map.put(c, map.getOrDefault(c, 0) + 1);
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}
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for (Map.Entry<Character, Integer> entry : map.entrySet()) {
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if (entry.getValue() == 1) {
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return entry.getKey();
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}
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}
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return ' ';
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}
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}
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```
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```java
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class Solution {
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public char firstUniqChar(String s) {
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char[] array = s.toCharArray();
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int[] ints = new int[256];
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for (char c : array) {
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ints[c]++;
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}
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for (char c : array) {
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if (ints[c] == 1) {
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return c;
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}
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}
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return ' ';
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}
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}
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```
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[58 - II. 左旋转字符串](https://leetcode-cn.com/problems/zuo-xuan-zhuan-zi-fu-chuan-lcof/)
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```java
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class Solution {
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public String reverseLeftWords(String s, int n) {
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return s.substring(n) + s.substring(0, n);
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}
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}
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```
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[Offer 58 - I. 翻转单词顺序](https://leetcode-cn.com/problems/fan-zhuan-dan-ci-shun-xu-lcof/)
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```java
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class Solution {
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public String reverseWords(String s) {
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String[] strings = s.trim().split(" ");
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StringBuilder sb = new StringBuilder();
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for (int i = strings.length - 1; i >= 0; i--) {
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if (strings[i].equals("")) {
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continue;
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}
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sb.append(strings[i]).append(" ");
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}
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return sb.toString().trim();
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}
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}
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```
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[67. 把字符串转换成整数](https://leetcode-cn.com/problems/ba-zi-fu-chuan-zhuan-huan-cheng-zheng-shu-lcof/)
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```java
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class Solution {
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public int strToInt(String str) {
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str = str.trim();
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if (str.length() == 0) {
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return 0;
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}
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boolean isMinus = false;
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char[] ch = str.toCharArray();
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if (ch[0] == '+' || ch[0] == '-' || Character.isDigit(ch[0])) {
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if (ch[0] == '+' || ch[0] == '-') {
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if (ch[0] == '-') {
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isMinus = true;
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}
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ch = Arrays.copyOfRange(ch, 1, ch.length);
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}
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int index = 0;
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long res = 0;
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while (index < ch.length && Character.isDigit(ch[index])) {
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res *= 10;
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res += ch[index] - '0';
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if (res > Integer.MAX_VALUE) {
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return isMinus ? Integer.MIN_VALUE : Integer.MAX_VALUE;
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}
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index++;
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}
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return isMinus ? -(int) res : (int) res;
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}
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return 0;
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}
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}
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```
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