May 10th

#include <string>#include <iostream>using namespace std;/*  Write a function that takes in a string and returns the length of the longest  prefix in which all characters are arranged in alphabetical order.  Examples:    alphaprefix("ransom") = 1    alphaprefix("google") = 3    alphaprefix("knotty") = 6*/int alphaprefix(string input) {  if(input.size() <= 1) return input.size();  int maxLen = 1;  int len = 1;  for(int i = 1; i < input.size(); ++i) {    if(input[i] >= input[i-1]) len++;    else break;  }  return len;}int main(void) {  cout << alphaprefix("ransom") << endl;  cout << alphaprefix("google") << endl;  cout << alphaprefix("knotty") << endl;}

This one is very similar to LeetCode's recover IP Address question, but much simpler! 

#include <iostream>#include <vector>using namespace std;/*  You are given a int[N] array num, count how many triplets(x, y, z) that  num[x] + num[y] +  num[z] < K  Assuming x < y < z  For example:  num[] = {5, 3, 6, 1, 8, 10}, K = 13  5 + 3 + 1 = 9 < 13  5 + 6 + 1 = 12 < 13  3 + 6 + 1 = 10 < 13  3 + 1 + 8 = 12 < 13 ----> return 4.*/int countTriplets(vector<int>& nums, int K) {  if(nums.size() < 3) return 0;  int count = 0;  for(int i = 0; i < nums.size() - 2; ++i) {    int target = nums[i];    for(int j = i + 1; j < nums.size() - 1; ++j) {      target += nums[j];      for(int k = j + 1; k < nums.size(); ++k) {        target += nums[k];        if(target < K) {          count++;        }        target -= nums[k];      }      target -= nums[j];    }  }  return count;}// Thought about it a bit. It seems that sort the nums doesn't actually affect the result.// The interviewer only asked for the final number. when we chose 3 numbers, they will always// have x < y < zint sortCountTriplets(vector<int>& nums, int K) {  if(nums.size() < 3) return 0;  sort(nums.begin(), nums.end());  int count = 0;  for(int i = 0; i < nums.size() - 2; ++i) {    int start = i + 1;    int end = nums.size() - 1;    while(start < end) {      int sum = nums[i] + nums[start] + nums[end];      if(sum < K) {        count += end - start;        start++;      } else end--;    }  }  return count;}int main(void) {  vector<int> nums{5, 3, 6, 1, 8, 10};  cout << countTriplets(nums, 13) << endl;}