best way to deal with big array or vector?

I suspect that accessing the same map from multiple threads will not improve the performance.

If you are able to change the creation of the input file ....

use unformatted I/O rather than text I/O. That should give
a significant performance improvment.

Quote:

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Originally Posted by Philip Nicoletti

If you are able to change the creation of the input file ....

use unformatted I/O rather than text I/O. That should give
a significant performance improvment.

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Unfortunately no, the input's format is fixed.

Quote:

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Originally Posted by dukevn

Now I am working on how to write the summary, not all the points like in the beginning. Starting from 0, the summary should report different intervals with different counts. For example, with input file like this

Code:

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a1        12        17
a1        20        25
a1        21        26
a2        13        18
a2        35        40
a1        16        21
a3        51        56
a3        65        70

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the output should look like

Code:

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a1        0        11        0
a1        12        15        1
a1        16        17        2
a1        18        19        1
a1        20        20        2
a1        21        21        3
a1        22        25        2
a1        26        26      1
a2        0        12        0
a2        13        18      1
a2      19      34      0
a2      35      40      1
...

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In order to archive something like above, I have to mix up a lot of if and else if when reading each of the map array. Here is the final code

Code:

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#include <map>
#include <vector>
#include <stdio.h>
#include <stdlib.h>
#include <fstream>
#include <iostream>
#include <sstream>
#include <string>

using namespace std;

struct Point {
  string Name;
  int xPos;

  Point(const string A,const int B) :
    Name(A),xPos(B) {}
};

struct PointCmp {
  bool operator()( const Point & b1, const Point & b2 ) {
    if ( b1.Name < b2.Name || ( b1.Name == b2.Name && b1.xPos < b2.xPos ) ) {
      return true;
    } else {
      return false;
    }
  }
};

typedef map<Point, int, PointCmp> mapPoint;

int main (int argc, char * const argv[]) {
  if ( argc == 1 ) {
    fprintf(stderr, "Usage: xyTest <input> <output>\n");
    return 1;
  }

  mapPoint mPoint;
  ifstream fin(argv[1]);
  string tempName;
  int x1, x2;
  while ( fin >> tempName >> x1 >> x2 ) {
    string temp;
    getline(fin,temp);
    for ( int i = x1; i <= x2; ++i ) {
      Point A(tempName,i);
      ++mPoint[A];
    }
  }
  fin.close();
   
  int tempCount;
  int tempPos;
  ofstream fout(argv[2]);
  for ( mapPoint::iterator i = mPoint.begin(), end = mPoint.end(); i != end; ++i ) {
    if ( i == mPoint.begin() ) {
      tempCount = i->second;
      tempName = (i->first).Name;
      tempPos = (i->first).xPos;
      fout << tempName << '\t' << 0 << '\t' <<  tempPos - 1 << '\t' << 0 << '\n';
      fout << tempName << '\t' << tempPos << '\t';
    } else if ( i->second == tempCount && tempName == (i->first).Name && (i->first).xPos == tempPos + 1 ) {
      ++tempPos;
      if ( i == --mPoint.end() ) {
        fout << tempPos << '\t' << tempCount << '\n';
      }
    } else if ( i->second == tempCount && (tempName == (i->first).Name) ) {
      fout << tempPos << '\t' << tempCount << '\n';
      fout << tempName << '\t' << tempPos + 1 << '\t' << (i->first).xPos - 1 << '\t' << 0 << '\n';
      tempPos = (i->first).xPos;
      fout << tempName << '\t' << tempPos << '\t';
    } else if ( tempName == (i->first).Name && ((i->first).xPos == tempPos + 1) ) {
      fout << tempPos << '\t' << tempCount << '\n';
      ++tempPos;
      fout << tempName << '\t' << (i->first).xPos << '\t';
      tempCount = i->second;
    } else if ( tempName == (i->first).Name ) {
      fout << tempPos << '\t' << tempCount << '\n';
      fout << tempName << '\t' << tempPos + 1 << '\t' <<  (i->first).xPos - 1 << '\t' << 0 << '\n';
      fout << tempName << (i->first).xPos << '\t';
    } else {
      fout << tempPos << '\t' << tempCount << '\n';
      tempCount = i->second;
      tempName = (i->first).Name;
      tempPos = (i->first).xPos;
      fout << tempName << '\t' << 0 << '\t' <<  tempPos - 1 << '\t' << 0 << '\n';
      fout << tempName << '\t' << tempPos << '\t';
    }
  }
  fout.close();
       
  return 0;
}

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It looks like a real mess inside the for loop, but I know nothing other than if/else if to do that. Any comment to shorten it or to make it look nicer are welcome.