58. Length of Last Word

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prolem

solution

option 1

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class Solution {
public:
    int lengthOfLastWord(string s) {
        
        int l =-1 , r = s.size()-1;
        while(r >l && s[r]==' ') r--;
        for(int i=0;i<=r;  ++i){    
            if(s[i] ==' ') l = i;
        }
        if(l==-1) return r+1;
        return r-l;
    }
};

option 2

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class Solution {
public:
    int lengthOfLastWord(string s) {
        int r= s.size()-1;
        while(r>-1 && s[r]==' ') r--;
        if(r==-1) return 0;
        for(int i=r;i>-1;i--){
            if(s[i] == ' ') return r-i;
        }
        return r+1;
    }
};

analysis

  • time complexity O(n)
  • space complexity O(1)