青蛙跳河

 

 

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
FILE *f1,*f2;
int flag[100];
int tiao[1000][1000];
int n;
int result = 0;
void Init()
{
    for(int i=1;i<=n;i++)
        if(i <= n/2)
            flag[i] = -1;
        else
            flag[i] = 1;
    flag[n/2+1] = 0;
}

void Print(int tiao[])
{
    for(int i=1;i<=n;i++)
        if(tiao[i]==-1)
            fprintf(f2,"> ");
        else if(tiao[i]==0)
            fprintf(f2,"_ ");
        else
            fprintf(f2,"< ");
    fprintf(f2,"\n");
}

void copy(int *a,int *b)
{
    for(int i=1;i<=n;i++)
        b[i] = a[i];
}

void swap(int i,int j)
{
    int temp = flag[i];
    flag[i] = flag[j];
    flag[j] = temp;
}

void Tiao(int index,int len)
{
    int sum = 0;
    for(int i=1;i<=n/2;i++)
        sum+=flag[i];
    copy(flag,tiao[len]);
    if(sum == n/2 && flag[n/2+1] ==0)
    {
        result ++;
        fprintf(f2,"%d:The flag Task is OK!!!\n",result);
        for(int i=0;i<=len;i++)
            Print(tiao[i]);
    }
    else
    {
        if(index-1 > 0 && flag[index-1] == -1)
        {
            swap(index,index-1);
            Tiao(index-1,len+1);
            swap(index,index-1);
        }

        if(index-2 > 0 && flag[index-2] == -1)
        {
            swap(index,index-2);
            Tiao(index-2,len+1);
            swap(index,index-2);
        }

        if(index+1 <= n && flag[index+1] == 1)
        {
            swap(index,index+1);
            Tiao(index+1,len+1);
            swap(index,index+1);
        }

        if(index+2 <= n && flag[index+2] == 1)
        {
            swap(index,index+2);
            Tiao(index+2,len+1);
            swap(index,index+2);
        }
    }
}

int main()
{
    f1 = fopen("1.in","r");
    f2 = fopen("1.out","w");
    fscanf(f1,"%d",&n);
    if(n%2==1)
    {
        Init();
        Tiao(n/2+1,0);
    }
    else
        fprintf(f2,"Please check the correctness of the n ! The n is Odd!");
    fclose(f1);
    fclose(f2);
    return 0;
}