Bridging signals POJ - 1631
'Oh no, they've done it again', cries the chief designer at the Waferland chip factory. Once more the routing designers have screwed up completely, making the signals on the chip connecting the ports of two functional blocks cross each other all over the place. At this late stage of the process, it is too expensive to redo the routing. Instead, the engineers have to bridge the signals, using the third dimension, so that no two signals cross. However, bridging is a complicated operation, and thus it is desirable to bridge as few signals as possible. The call for a computer program that finds the maximum number of signals which may be connected on the silicon surface without crossing each other, is imminent. Bearing in mind that there may be thousands of signal ports at the boundary of a functional block, the problem asks quite a lot of the programmer. Are you up to the task?
A typical situation is schematically depicted in figure 1. The ports of the two functional blocks are numbered from 1 to p, from top to bottom. The signal mapping is described by a permutation of the numbers 1 to p in the form of a list of p unique numbers in the range 1 to p, in which the i:th number specifies which port on the right side should be connected to the i:th port on the left side.Two signals cross if and only if the straight lines connecting the two ports of each pair do.Input
Output
Sample Input
4 6 4 2 6 3 1 5 10 2 3 4 5 6 7 8 9 10 1 8 8 7 6 5 4 3 2 1 9 5 8 9 2 3 1 7 4 6
Sample Output
3 9 1 4
题意:~~~~解释一下input,第i个位置连着p[i],第一个案例,1-4,2-2,3-6,4-3,5-1,6-5.
典型的LIS。
1 #include<cstdio> 2 #include<cstring> 3 #include<iostream> 4 #include<algorithm> 5 #define INF 1e8 6 using namespace std; 7 8 const int maxn=40005; 9 10 int n; 11 int p[maxn],dp[maxn]; 12 13 void solve(){ 14 fill(dp,dp+n,INF); 15 for(int i=0;i<n;i++) *lower_bound(dp,dp+n,p[i])=p[i]; 16 int ans; 17 ans=lower_bound(dp,dp+n,INF)-dp; 18 cout<<ans<<endl; 19 } 20 21 int main() 22 { int cases; 23 cin>>cases; 24 while(cases--){ 25 cin>>n; 26 for(int i=0;i<n;i++) scanf("%d",&p[i]); 27 //sort(p,p+n); 28 29 solve(); 30 } 31 }