leetcode：2023/4/6

每日一题

1017.负二进制转换

class Solution {public String baseNeg2(int n) {if(n==0){return "0";}int[] bits=new int[32];for(int i=0;i<32&&n!=0;i++){if((n&1)!=0){bits[i]++;if((i&1)!=0){bits[i+1]++;}}n>>=1;}int carry=0;for(int i=0;i<32;i++){int val=carry+bits[i];bits[i]=val&1;carry=(val-bits[i])/(-2);}int pos=31;StringBuilder res=new StringBuilder();while(pos>=0&&bits[pos]==0){pos--;}while(pos>=0){res.append(bits[pos]);pos--;}return res.toString();}
}

class Solution {public String baseNeg2(int n) {if(n==0){return "0";}String ans="";for(int i=0;n>0;i++){ans=(n&1)+ans;if((i&1)==1){n+=(n&1)<<1;}n>>=1;}return ans;}
}

效率不高

344.翻转字符串

class Solution {public void reverseString(char[] s) {int n=s.length;for(int left=0,right=n-1;left<right;++left,--right){char tmp=s[left];s[left]=s[right];s[right]=tmp;}}
}

557. 反转字符串中的单词 III

class Solution {public String reverseWords(String s) {StringBuffer ret = new StringBuffer();int length = s.length();int i = 0;while (i < length) {int start = i;while (i < length && s.charAt(i) != ' ') {i++;}for (int p = start; p < i; p++) {ret.append(s.charAt(start + i - 1 - p));}while (i < length && s.charAt(i) == ' ') {i++;ret.append(' ');}}return ret.toString();}
}