68 lines
1.5 KiB
C
68 lines
1.5 KiB
C
/* mbinary
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#########################################################################
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# File : permute_cantor.c
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# Author: mbinary
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# Mail: zhuheqin1@gmail.com
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# Blog: https://mbinary.xyz
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# Github: https://github.com/mbinary
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# Created Time: 2018-11-17 11:25
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# Description:
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#########################################################################
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*/
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#include<stdio.h>
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//使用康托展开计算全排列, 下面存储的是0!,1!,2!...(n-1)!
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long long int fac[100]={};
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void calFac(int n)
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{
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int i;
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fac[0]=1;
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for(i=1;i<=n;i++){
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fac[i]=i*fac[i-1];
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}
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}
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void permute(int *arr,int n,int sum)
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{
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/*sum表示全排列由小到大排序后的名次,从0 开始计数, 由名次求出 n位的排列存储到 arr 中*/
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int i,j,ct=0,k, ct2;
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int flag[n];
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for(i=0;i<n;i++)flag[i]=1;
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for(i=n-1;i>=0;i--){
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for(j=i;j>=0;j--){
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if(j*fac[i]<=sum){
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ct2=0;
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for(k=0;k<n;++k){
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//printf("i%d j%d k%d\n",i,j,k);
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if(flag[k]==1)ct2++;
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if(ct2>j)break;
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}
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arr[ct++] = k;
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flag[k]=0;
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sum -=j*fac[i];
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break;
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}
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}
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}
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}
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void printArr(int *p,int n)
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{
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for(int i=0;i<n;++i)printf("%d, ",p[i]);
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printf("\n");
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}
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int main()
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{
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int n = 5,arr[n];
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calFac(n);
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for(int i=0;i<5;++i)arr[i]=i;
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for(int i=0;i<fac[n];++i){
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printArr(arr,n);
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permute(arr,n,i);
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}
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return 0;
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}
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