POJ 3041 Asteroids(二分图模板题)
Posted songorz
tags:
篇首语:本文由小常识网(cha138.com)小编为大家整理,主要介绍了POJ 3041 Asteroids(二分图模板题)相关的知识,希望对你有一定的参考价值。
Bessie wants to navigate her spaceship through a dangerous asteroid field in the shape of an N x N grid (1 <= N <= 500). The grid contains K asteroids (1 <= K <= 10,000), which are conveniently located at the lattice points of the grid.
Fortunately, Bessie has a powerful weapon that can vaporize all the asteroids in any given row or column of the grid with a single shot.This weapon is quite expensive, so she wishes to use it sparingly.Given the location of all the asteroids in the field, find the minimum number of shots Bessie needs to fire to eliminate all of the asteroids.
Fortunately, Bessie has a powerful weapon that can vaporize all the asteroids in any given row or column of the grid with a single shot.This weapon is quite expensive, so she wishes to use it sparingly.Given the location of all the asteroids in the field, find the minimum number of shots Bessie needs to fire to eliminate all of the asteroids.
Input
* Line 1: Two integers N and K, separated by a single space.
* Lines 2..K+1: Each line contains two space-separated integers R and C (1 <= R, C <= N) denoting the row and column coordinates of an asteroid, respectively.
* Lines 2..K+1: Each line contains two space-separated integers R and C (1 <= R, C <= N) denoting the row and column coordinates of an asteroid, respectively.
Output
* Line 1: The integer representing the minimum number of times Bessie must shoot.
Sample Input
3 4 1 1 1 3 2 2 3 2
Sample Output
2
Hint
INPUT DETAILS:
The following diagram represents the data, where "X" is an asteroid and "." is empty space:
X.X
.X.
.X.
OUTPUT DETAILS:
Bessie may fire across row 1 to destroy the asteroids at (1,1) and (1,3), and then she may fire down column 2 to destroy the asteroids at (2,2) and (3,2).
The following diagram represents the data, where "X" is an asteroid and "." is empty space:
X.X
.X.
.X.
OUTPUT DETAILS:
Bessie may fire across row 1 to destroy the asteroids at (1,1) and (1,3), and then she may fire down column 2 to destroy the asteroids at (2,2) and (3,2).
题解:二分图模板题:
参考代码:
1 #include<iostream> 2 #include<cstdio> 3 #include<cstring> 4 #include<cmath> 5 #include<cstdlib> 6 #include<algorithm> 7 #include<queue> 8 #include<deque> 9 #include<stack> 10 #include<set> 11 #include<vector> 12 #include<map> 13 using namespace std; 14 const int maxn=520; 15 int n,m,ok[maxn]; 16 bool a[maxn][maxn],vis[maxn]; 17 18 bool Find(int x) 19 { 20 for(int i=1;i<=n;i++) 21 { 22 if(a[x][i]&&!vis[i]) 23 { 24 vis[i]=true; 25 if(!ok[i]||Find(ok[i])) 26 { 27 ok[i]=x; 28 return true; 29 } 30 } 31 } 32 return false; 33 } 34 int maxP() 35 { 36 int ans=0; 37 memset(ok,0,sizeof(ok)); 38 for(int i=1; i<=n; i++) 39 { 40 memset(vis,false,sizeof(vis)); 41 if(Find(i)) ans++; 42 } 43 return ans; 44 } 45 int main() 46 { 47 cin>>n>>m; 48 49 memset(a,false,sizeof(a)); 50 int x,y,z; 51 while(m--) 52 { 53 cin>>x>>y; 54 a[x][y]=true; 55 } 56 int ans=maxP(); 57 printf("%d ",ans); 58 59 60 return 0; 61 }
以上是关于POJ 3041 Asteroids(二分图模板题)的主要内容,如果未能解决你的问题,请参考以下文章