Day 8 of Code Random Recording Algorithm Training Camp|344. Reverse String| Sword Pointer Offer 05. Replace Space| 151. Flip Words in String| Sword Pointer Offer58-II. Left Rotate String

344. Reverse a String

class Solution {
    
    
public:
    void reverseString(vector<char>& s) {
    
    
        int left=0,right=s.size()-1;
        while(left<right){
    
    
            swap(s[left],s[right]);
            left++;
            right--;
        }
    }
};

Sword Pointer Offer 05. Replace spaces

class Solution {
    
    
public:
    string replaceSpace(string s) {
    
    
        int count=0;
        for(char a:s){
    
    
            if(a==' '){
    
    
                count++;
            }
        }
        int i=s.size()-1;
        s.resize(s.size()+count*2);
        int j=s.size()-1;
        for(i,j;i>=0;i--){
    
    
            if(s[i]==' '){
    
    
                s[j--]='0';
                s[j--]='2';
                s[j--]='%';
            }else{
    
    
                s[j--]=s[i];
            }
        }
        return s;
    }
};

151. Flip words in a string

class Solution {
    
    
public:
    string reverseWords(string s) {
    
    
        int k=0;
        for(int i=0;i<s.size();++i){
    
    
            if(s[i]!=' '){
    
    
                if(k!=0)s[k++]=' ';
                while(i<s.size()&&s[i]!=' '){
    
    
                    s[k++]=s[i++];
                }
            }
        }
        s.resize(k);
        reverse(s.begin(),s.end());
        for(int i=0,j=0;i<=s.size();i++){
    
    
            if(s[i]==' '||i==s.size()){
    
    
                reverse(s.begin()+j,s.begin()+i);
                j=i+1;
            }
        }
        return s;
    }
};

Sword Pointing to Offer58-II. Left Rotate String

class Solution {
    
    
public:
    string reverseLeftWords(string s, int n) {
    
    
        reverse(s.begin(), s.begin() + n);
        reverse(s.begin() + n, s.end());
        reverse(s.begin(), s.end());
        return s;
    }
};