LeetCode刷题记录——day7

1、https://leetcode.cn/problems/reverse-words-in-a-string/description/?envType=study-plan-v2&envId=top-interview-150

class Solution {
public:
    string reverse(string s){
        string ans;
        for(int i=s.length()-1;i>=0;i--){
            ans=ans+s[i];
        }
        return ans;
    }
    string reverseWords(string s) {
        string temp = "";
        string ans;
        int len = s.length();
        int began = s.length() - 1, end = 0;
        int sign = 1;
        while (s[began] == ' ') {
            began--;
        }
        while (s[end] == ' ') {
            end++;
        }
        for(int i=began;i>=end;i--){
            if(s[i]!=' '){
                temp=temp+s[i];
                sign=0;
            }
            if(s[i]==' '&&sign==0){
                ans=ans+reverse(temp)+" ";
                temp="";
                sign=1;
            }
        }
        ans=ans+reverse(temp);
        return ans;
    }
};

2、https://leetcode.cn/problems/zigzag-conversion/?envType=study-plan-v2&envId=top-interview-150
创建一个二维数组就比较简单了，但是记得1的特殊情况

class Solution {
public:
    string convert(string s, int numRows) {
        if(numRows==1) return s;
        vector<string> temp(numRows);
        int len=s.length();
        int sign_cir=0,sign_num=0;
        for(int i=0;i<len;i++){
            if(sign_num<0){
                sign_num=1;
                sign_cir++;
            }else if(sign_num>numRows-1){
                sign_num=numRows-2;
                sign_cir++;
            }
            if(sign_cir%2==0){
                temp[sign_num]+=s[i];
                sign_num++;
            }else{
                temp[sign_num]+=s[i];
                sign_num--;
            }
        }
        string ans;
        for(int i=0;i<numRows;i++)
            ans+=temp[i];
        return ans;
    }
};