Random selection of tracks?

Question

C++ / C#

Condition one hour i.e. 3600 seconds, length in seconds, you need to somehow pick up the hour so that it does not exceed 3601 and there is a track with a duration of 12 seconds that can be inserted at any place in the sample, the sample should be different from the program launch (i.e. you need random) apparently you need set a limit to which random tracks are collected, and then those that are suitable are added, for example, we collect 55 minutes randomly, and then we select from 5 minute ones, although how do we collect exactly 55 minutes? I xs to be honest. Number of tracks vector2->size(); those. we need another vector in which we will throw off our sample

struct Type
{
  std::string filename;
  float length;
};
std::vector<Type> *vector2 = new std::vector<Type>();

complete program code

#include <iostream>
#include <fstream>
#include <vector>
#include <Windows.h>
#include <string>
#include <cstdlib>
//#include <sstream>
//#include <locale>
#include <time.h>
#include "mp3.h"
#include "mp3frame.h"
//#define _CRT_SECURE_NO_WARNINGS 
long int rez = 0;
struct Type
{
  std::string filename;
  float length;
};
void GetFileList(LPTSTR sPath, LPTSTR sExt, LPTSTR sEXT, std::vector<Type> *v);

int main(int argc, char* argv[])
{
  
  std::vector<Type> *vector = new std::vector<Type>();
  std::vector<Type> *vectortalk = new std::vector<Type>();
  char sPath[MAX_PATH] = "Z:\\Автоматизация\\музыка для радио от Сергея Косякова";
  char sPath2[MAX_PATH] = "Z:\\Радио";
  char sExt[10] = "mp3";
  char sEXT[10] = "MP3";
  GetFileList(sPath, sExt, sEXT, vector);
  printf("rez= %d\n", rez);
  rez = 0;
  GetFileList(sPath2, sExt, sEXT, vectortalk);
  printf("rez= %d\n", rez);

  std::ofstream fout;
  fout.open("playlist.m3u8");
  if (!fout.is_open())
  {
    std::cout << "Can't open file" << std::endl;
    exit(EXIT_FAILURE);
  }
  fout.write("#EXTM3U\n", strlen("#EXTM3U\n"));
  fout.write("#EXTINF:", strlen("#EXTINF:"));
  fout.write("12", strlen("12"));
  fout.write(",", strlen(","));
  fout.write((*vector)[0].filename.c_str(), (*vector)[0].filename.size());
  fout.write("\n", strlen("\n"));
  fout.write((*vector)[0].filename.c_str(), (*vector)[0].filename.size());
  fout.write("\n", strlen("\n"));

  /*
  std::string f_str;
  for (int i = 0;i < vector->size();i++)
  {
    fout.write(vector->at(i).filename.c_str(), vector->at(i).filename.size());
    fout.write("\n", 1);
    MP3 mp3(vector->at(i).filename.c_str());
    (*vector)[i].length = mp3.get_len();
    f_str = std::to_string(mp3.get_len());
    fout.write(f_str.c_str(),f_str.size());
    fout.write("\n", 1);
  }
  for (int i = 0;i < vectortalk->size();i++)
  {
    fout.write(vectortalk->at(i).filename.c_str(), vectortalk->at(i).filename.size());
    fout.write("\n", 1);
    MP3 mp3(vectortalk->at(i).filename.c_str());
    (*vectortalk)[i].length = mp3.get_len();
    f_str = std::to_string(mp3.get_len());
    fout.write(f_str.c_str(), f_str.size());
    fout.write("\n", 1);
  }
  */

  fout.close();

  Type elem;
  
  MP3 mp3__("C:\\Users\\User\\Desktop\\РАДИО\\джингл1.mp3");
  std::cout << mp3__.get_name();
  std::cout << mp3__.get_artist();
  std::cout << mp3__.get_len() << " length\n";
  std::cout << mp3__.get_bitrate() << " bitrate\n";
  //cout << mp3.get_pic();
  //mp3.save_pic("where/you/want/to/save.jpg");
  elem.filename = "C:\\Users\\User\\Desktop\\РАДИО\\джингл1.mp3";
  elem.length = mp3__.get_len();
  std::vector<Type> *vector2 = new std::vector<Type>();

  vector2->push_back(elem);
  
  setlocale(LC_ALL, "Russian");

  std::ifstream fin("playlist2.m3u8");
  if (!fin.is_open())
  {
    std::cout << "File not found!" << std::endl;
  }
  std::string str="";
  while (std::getline(fin,elem.filename))
  {
    std::getline(fin, str);
    elem.length = std::stof(str);
    if(elem.length != 0.0)
      vector2->push_back(elem);
  }
  fin.close();
  
  int sum = 0;
  for (int i = 0;i < vector2->size();i++)
    if ((*vector2)[i].length == 0.0)
      sum++;
  
  std::cout <<"size="<< vector2->size() << std::endl<<"0: " <<sum<< std::endl;
  
  std::cout << (*vector2)[0].filename << std::endl << (*vector2)[0].length << std::endl;
  std::cout << (*vector2)[vector2->size()-1].filename << std::endl << (*vector2)[vector2->size() - 1].length << std::endl;
  

  //setlocale(LC_ALL, "ru_RU.UTF-8");
  std::vector<Type> *vector3 = new std::vector<Type>();
  std::ifstream fin2("playlist3.m3u8");
  if (!fin2.is_open())
  {
    std::cout << "File not found!" << std::endl;
  }
  while (std::getline(fin2, elem.filename))
  {
    std::getline(fin2, str);
    elem.length = std::stof(str);
    if (elem.length != 0.0)
      vector3->push_back(elem);
  }
  fin2.close();
  
  sum = 0;
  for (int i = 0;i < vector3->size();i++)
    if ((*vector3)[i].length == 0.0)
      sum++;
  
  std::cout << "size=" << vector3->size() << std::endl << "0: " << sum << std::endl;
  
  std::cout << (*vector3)[0].filename << std::endl << (*vector3)[0].length << std::endl;
  

  
  vector->clear();
  vectortalk->clear();
  std::cin.get();
  return 0;
}
int Random(std::vector<Type> *vector)
{
  int min = 0, max = vector->size()-1;
  srand(time(0));
  return min + rand() % (max - min + 1);
}
void GetFileList(LPTSTR sPath, LPTSTR sExt, LPTSTR sEXT,std::vector<Type> *v) {

  WIN32_FIND_DATA pFILEDATA;
  HANDLE hFile = FindFirstFile(strcat(sPath, "\\*.*"), &pFILEDATA);

  //!!!!!!!!!!!!!!!!!!!!!!!!!!!!Необходимо именно здесь прописывать длину пути!!!!!!!!!!!!!!!!!!!!!!!
  sPath[strlen(sPath) - strlen(strstr(sPath, "*.*"))] = '\0';
  //Если пропишем после if (как предлагает Юра), то тогда, если вдруг натыкаемся на системную директорию
  // или файл, то FindFirstFile возвращает -1. Следовательно, всё, что выплнняется по условию
  //(hFile!=INVALID_HANDLE_VALUE) не выолнится и в частности, не будет поставлен конец строки!
  //А это значит, что по выходу из  рекурсивной функции GetFileList в том месте, где мы восстанавливаем
  //Длину, она будет восстановлена неправильно
  if (hFile != INVALID_HANDLE_VALUE) {
    char * chBuf;
    //sPath[strlen(sPath) - strlen(strstr(sPath,"*.*"))] = '\0';
    do {
      //Пропускаем . и ..
      if (strlen(pFILEDATA.cFileName) == 1 && strchr(pFILEDATA.cFileName, '.') != NULL)
        if (FindNextFile(hFile, &pFILEDATA) == 0)
          break;
      if (strlen(pFILEDATA.cFileName) == 2 && strstr(pFILEDATA.cFileName, "..") != NULL)
        if (FindNextFile(hFile, &pFILEDATA) == 0)
          break;
      //Если нашли директорию, запускаем поиск в ней рекурсивный поиск
      if (pFILEDATA.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) {
        GetFileList(strcat(sPath, pFILEDATA.cFileName), sExt, sEXT,v);

        //!!!!!!!!!!!!!!!!!!!!!!!!!!!!!оБЯЗАТЕЛЬН востанавливать дллину пути................................     
        sPath[strlen(sPath) - strlen(pFILEDATA.cFileName) - 1] = '\0';
      }
      else {
        //Проверяем на соотвествие sExt расширения pFILEDATA.cFileName
        if ((chBuf = strrchr(pFILEDATA.cFileName, '.'))) {
          if (strstr(chBuf + 1, sExt) || strstr(chBuf + 1, sEXT)) {
            //Если не будем использовать CharToOem() то на экране русский шрифт каракулями выйдет
            CharToOem(sPath, sPath);
            //printf("%s", sPath);
            OemToChar(sPath, sPath);
            CharToOem(pFILEDATA.cFileName, pFILEDATA.cFileName);
            //printf("%s\n", pFILEDATA.cFileName);
            
            Type type;
            if (rez == 14)
              bool b = true;
            OemToChar(pFILEDATA.cFileName, pFILEDATA.cFileName);
            std::string str = pFILEDATA.cFileName;
            type.filename = sPath + str;
            v->push_back(type);
            //printf("%s\n",v->at(rez).filename);
            //printf("%d\n", rez);
            
            rez++;
          }
        }
      }
    } while (FindNextFile(hFile, &pFILEDATA));
  }
}

mp3 class link https://github.com/TheOnlyCaky/libmp3

Answer 1

If you so insist on the algorithms tag, then you are here
https://ru.wikipedia.org/wiki/Problem_cutting