36 lines
728 B
C++
36 lines
728 B
C++
#include <cstdio>
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#define LL long long
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LL solve(LL n,LL k,LL s=1)
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{
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if(k==1) return (n-1+s)%n;
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LL ans=0;
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for(LL i=2;i<=n;)
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{
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if(ans+k<i)
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{
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LL leap;
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if((i-ans-1)%(k-1)==0) leap=(i-ans-1)/(k-1)-1;
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else leap=(i-ans-1)/(k-1);
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if(i+leap>n) return ((ans+(n+1-i)*k)+s)%n;
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i+=leap;
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ans+=leap*k;
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}
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else
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{
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ans=(ans+k)%i;
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i++;
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}
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}
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return (ans+s)%n;
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}
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int main()
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{
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LL n,k;
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while(scanf("%I64d%I64d",&n,&k)!=EOF)
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{
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LL ans=solve(n,k);
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if(ans==0) printf("%I64d\n",n);
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else printf("%I64d\n",ans);
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}
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}
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