151. Reverse Words in a String

Given an input string, reverse the string word by word.

For example,

Given s = "

the sky is blue

",

return "

blue is sky the

".

Update (2015-02-12):

For C programmers: Try to solve it in-place in O(1) space.

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class Solution {

public:

void reverseWords(string &s) {

reverse(s.begin(),s.end());

int before=0;

//int end=0;

for(int i=0;i<s.size();i++){

if(s[i]==' '){

while(s[i+1]==' '){

s.erase(s.begin()+i+1);

}

reverse(s.begin()+before,s.begin()+i);

before=i+1;

//end=i;

}

}

reverse(s.begin()+before,s.end());

int j=0;

while(s[j]==' '){

s.erase(s.begin()+j);

//j++;

}

int end=s.size();

while(s[end-1]==' '){

s.erase(s.begin()+end-1);

}

if(s[end-1]==' '){

s.erase(s.begin()+end);

}

}

};