43 lines
644 B
C++
43 lines
644 B
C++
#include<stdio.h>
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#include<string.h>
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int a[1002];
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int lowbit(int x)
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{
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return x&(-x);
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}
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void add(int x)
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{
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while(x<=1000)
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{
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++a[x];
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x=x+lowbit(x);
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}
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}
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int getsum(int x)
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{
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int sum=0;
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while(x>0)
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{
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sum=sum+a[x];
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x=x-lowbit(x);
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}
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return sum;
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}
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int main()
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{
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int i,j,n,x,sum;
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while(scanf("%d",&n)==1)
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{
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sum=0;
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memset(a,0,sizeof(a));
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for(i=1;i<=n;i++)
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{
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scanf("%d",&x);
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sum=sum+(i-1-getsum(x));
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add(x);
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}
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printf("%d\n",sum);
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}
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return 0;
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}
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