541. Reverse String II

Given a string and an integer k, you need to reverse the first k characters for every 2k characters counting from the start of the string. If there are less than k characters left, reverse all of them. If there are less than 2k but greater than or equal to k characters, then reverse the first k characters and left the other as original.

Example:

Input: s = "abcdefg", k = 2 Output: "bacdfeg"

Restrictions: The string consists of lower English letters only.Length of the given string and k will in the range [1, 10000]

直接上代码：

char* reverseStr(char* s, int k) { int temp,length; int i,j; length=strlen(s); temp=length/(2*k); for(i=0;i<temp;i++){ reverse(s,i*2*k,i*2*k+k-1); } if(length%(2*k)<k){ reverse(s,temp*2*k,length-1); }else{ reverse(s,temp*2*k,temp*2*k+k-1); } return s; } void reverse(char *s,int m,int n){ int mid,i; char temp; mid=(m+n)/2; if(m!=n){ for(i=m;i<=mid&&m<=n;i++){ temp=s[m]; s[m]=s[n]; s[n]=temp; m++; n--; } } }