73 lines
1.7 KiB
C++
73 lines
1.7 KiB
C++
#include<cstdio>
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#include<cstring>
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#include<algorithm>
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using namespace std;
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const int MAXN =10000+100;
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int a[MAXN];
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int dmin[MAXN][20];
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void initMin(int n,int d[])
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{
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for(int i=0; i<=n; i++)dmin[i][0]=d[i];
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for(int j=1; (1<<j)<=n; j++)
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for(int i=1; i+(1<<j)-1<=n; i++)
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dmin[i][j] = min(dmin[i][j-1] , dmin[i+(1<<(j-1))][j-1]);
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}
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int getMin(int L,int R)
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{
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int k=0;
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while((1<<(k+1))<=R-L+1)k++;
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return min(dmin[L][k] , dmin[R-(1<<k)+1][k]);
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}
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struct node
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{
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int p,d;
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bool operator <(const node &b)const
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{
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return p<b.p || (p==b.p && d<b.d);
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}
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} node1[MAXN],node2[MAXN];
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int main()
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{
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int n;
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while(scanf("%d",&n)==1&&n)
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{
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for(int i =0; i<=10000+100; i++)
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a[i]=1000000;
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for(int i=1; i<=n; i++)
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{
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int p,d;
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scanf("%d%d",&p,&d);
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p++;
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d++;
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node1[i].p=p;
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node1[i].d=d;
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a[p] = min(a[p],d);
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}
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initMin(MAXN,a);
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int cnt=0;
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for(int i=1; i<=n; i++)
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{
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int p,d;
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p = node1[i].p;
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d = node1[i].d;
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if(p==1)
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{
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node2[++cnt] =node1[i];
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}
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else
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{
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int d_min = getMin(1,p-1);
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if(d<=d_min)
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{
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node2[++cnt] =node1[i];
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}
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}
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}
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sort(node2+1,node2+1+cnt);
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printf("%d\n",cnt);
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for(int i=1; i<=cnt; i++)
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printf("%d %d\n",node2[i].p-1,node2[i].d-1);
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}
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return 0;
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}
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