gistfile1.c

#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/time.h>

extern double drand48();
int Z;
int M;
int sizeLattice;
int N;
double SumR2;

int main(int argc, char* argv[])
{
	M = (argc >1) ? atoi(argv[1]) : 2;
	int seed;
	seed=time(NULL);
	srand48(seed);
	for(N=1;N<=M;N++){
		walk();
	}
  
}

void printlattice(int* lattice){
	int i,j;
	for(i=0;i<2*M+1;i++){
		for(j=0;j<2*M+1;j++) printf("%d ",lattice[i*(2*M+1)+j]);
		printf("\n");
	}
}

walk(){
    Z = 0.0;
    SumR2 = 0.0;
    int start, end;
    FILE *file1;
    start = time(NULL);
    int StepX[N];
    int StepY[N];
    int i;
   	sizeLattice = (2*M+1)*(2*M+1);
	int* lattice = malloc(sizeLattice*sizeof(int));
	for(i=0;i<sizeLattice;i++) lattice[i] = 0;
	lattice[M*(2*M+1)+M]=1;
	printlattice(lattice);
    StepX[0] = 0;
    StepY[0] = 0;
    //printlattice();
    go(1, 0, 1, StepX, StepY,lattice);
    end = time(NULL);
    file1 = fopen("polymers.txt","a+");
    printf("%i\t%u\t\t%f\t%i\n",N, 4*Z, SumR2/Z, end-start);
    fprintf(file1,"%i\t%u\t\t%f\t%i\n",N, 4*Z, SumR2/Z, end-start);
    fclose(file1);
}



go(int x, int y, int n, int *PrevX, int *PrevY, int* lattice)
{
	int posX = M+x;
	int posY = M+y;
	printf("%d,%d\n",posX,posY);
	lattice[posX*(2*M+1)+posY] = 1;
	printlattice(lattice);
	int StepX[N];
	int StepY[N];
	int i;
	
	for(i=0;i<n;i++){
		StepX[i] = PrevX[i];
		StepY[i] = PrevY[i];
	}
	/*
	for(i=n-1;i>=0;i--){
		if(StepX[i]==x &&StepY[i]==y){
			return;
		}
	}
	*/
	
	StepX[n] = x;
	StepY[n] = y;

	for(i=0;i<n;i++) printf("(%d,%d)-",StepX[i],StepY[i]);
	printf("\n");

	if(n==N){
		Z++;
		SumR2 += x*x + y*y;
//		lattice[(M+x)*(2*M+1)+M+y]=0;
		/*
		int i;
		//printf("\n step: ");
		//for(i=0;i<=N;i++)
		for(i=0;i<n-1;i++) {
		//printf("(%d,%d) - ",StepX[N-i],StepY[N-i]);
		lattice[M+StepX[N-i]][M+StepY[N-i]]=0;
		}
		printf("\n");
		*/
	}
	else{
		int before = 0;
		for(i=n-1;i>=0;i--){
			if(StepX[i]==x &&StepY[i]==y+1){

				before = 1;
				break;
			}
		}
		if (before == 0) go(x, y+1, n+1, StepX, StepY,lattice);
	    before = 0;
		for(i=n-1;i>=0;i--){
			if(StepX[i]==x &&StepY[i]==y-1){
				before = 1;
				break;
			}
		}
		if (before == 0) go(x, y-1, n+1, StepX, StepY,lattice);
		before = 0;
		for(i=n-1;i>=0;i--){
			if(StepX[i]==x+1 &&StepY[i]==y){
				before = 1;
				break;
			}
		}
		if (before == 0) go(x+1, y, n+1, StepX, StepY,lattice);
		before = 0;
		for(i=n-1;i>=0;i--){
			if(StepX[i]==x-1 &&StepY[i]==y){
				before = 1;
				break;
			}
		}
		if (before == 0) go(x-1, y, n+1, StepX, StepY,lattice);
	}
}