class Solution {
public:
void reverse(string &s,int l,int r){
while(l<r){
char tmp=s[r];
s[r]=s[l];
s[l]=tmp;
l++;
r--;
}
}
string reverseLeftWords(string s, int n) {
int sz=s.size();
n=n%sz;
reverse(s,0,n-1);
reverse(s,n,sz-1);
reverse(s,0,sz-1);
return s;
}
};