LeetCode Weekly Contest 23

LeetCode Weekly Contest 23

1. 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]

实现

#include <iostream>
#include <algorithm>

using namespace std;

class Solution {
public:
string reverseStr(string s, int k) {
int k2 = k * 2;
int counter = 0;
int size = s.length();
string result = "";

while(1) {
if (counter + k > size) {
string tmp(s.begin()+counter, s.end());
reverse(tmp.begin(), tmp.end());
result += tmp;
return result;
} else {
if (counter + k2 <= size) {
string tmp(s.begin()+counter, s.begin()+counter+k);
reverse(tmp.begin(), tmp.end());
result += tmp;
string tmp2(s.begin()+counter+k, s.begin()+counter+k2);
result += tmp2;
counter += k2;
} else {
string tmp(s.begin()+counter, s.begin()+counter+k);
reverse(tmp.begin(), tmp.end());
result += tmp;
counter += k;
string tmp2(s.begin()+counter, s.end());
result += tmp2;
return result;
}
}
}
}
};

int main() {
Solution* solution = new Solution();
cout << solution->reverseStr("abcdefg", 10) << endl;
return 0;
}

2. Minimum Time Difference

3. Construct Binary Tree from String

4. Word Abbreviation