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leetcode3.java
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59 lines (54 loc) · 1.81 KB
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package leetcode;
import java.util.HashMap;
public class leetcode3 {
//暴力法
public int lengthOfLongestSubstring1(String s) {
if(s.length()==0) return 0;
int [] nums=new int[26];
char[] chars=s.toCharArray();
int length=1;
int maxlength=0;
for(int i=0;i<chars.length;i++){
for (int j = i; j <chars.length ; j++) {
if (nums[(chars[j]-' ')%26]==0){
maxlength++;
nums[(chars[j]-' ')%26]=1;
}else{
if (maxlength>length) length=maxlength;
maxlength=0;
for (int k = 0; k <nums.length ; k++) {
nums[k]=0;
}
break;
}
}
}
return length;
}
/*
* 滑动窗口法：
* abcabcbb/bbbb
* 应用HashMap Key-Value属性记录每一个字符出现的索引位置
* left记录不含重复字符的子字符串的左边界
* 如果出现了相同的字符,此时的i>left
* left 变为之前出现的重复字符的位置
* */
public int lengthOfLongestSubstring(String s) {
if(s.length()==0) return 0;
HashMap<Character, Integer> map = new HashMap<Character, Integer>();
int max=0;
int left=0;
for (int i = 0; i <s.length(); i++) {
if (map.containsKey(s.charAt(i))){
left=Math.max(left,map.get(s.charAt(i))+1); //左边界变化
}
map.put(s.charAt(i),i); //覆盖重复字符的新位置
max=Math.max(max,i-left+1);
}
return max;
}
public static void main(String[] args) {
(new leetcode3()).lengthOfLongestSubstring1("abcabcbb");
//System.out.println(('a'-' ')%26);
}
}