49 lines
1.2 KiB
C++
49 lines
1.2 KiB
C++
#include<stdio.h>
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int a[1000],b[1000],c[1000];
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int main(){
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int t,n,i,j,k,a0,b0,c0;
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scanf("%d",&t);
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while(t--){
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scanf("%d",&n);
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if(n<5){
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if(n==3) printf("6\n1 2\n5 3 4\n");
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else printf("9\n5 4\n1 3\n8 2 6 7\n");
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continue;
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}
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if(n&1){
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i=3*(n-2);
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a0=b0=c0=0;
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while(i>0){
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c[c0++]=i--;
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b[b0++]=i--;
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a[a0++]=i--;
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if(i<=0) break;
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a[a0++]=i--;
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b[b0++]=i--;
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c[c0++]=i--;
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}
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}
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else{
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i=3*(n-2);
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c[0]=2;c[1]=6;
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b[0]=3;b[1]=4;
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a[0]=1;a[1]=5;
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a0=b0=c0=2;
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while(i>6){
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c[c0++]=i--;
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b[b0++]=i--;
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a[a0++]=i--;
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a[a0++]=i--;
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b[b0++]=i--;
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c[c0++]=i--;
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}
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}
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printf("%d\n",3*(n-1));
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for(i=0;i<a0;i++) printf("%d %d\n",a[i],b[i]);
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printf("%d",3*(n-1)-1);
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for(i=0;i<c0;++i) printf(" %d",c[i]);
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printf(" %d\n",3*(n-1)-2);
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}
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return 0;
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}
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