Asteroids (最小覆盖)
来源:互联网 发布:mysql dump 导出表 编辑:程序博客网 时间:2024/06/03 19:21
题目很简单,但是需要推到出二分图最大匹配 = 最小覆盖
最小覆盖:证明过程http://blog.sina.com.cn/s/blog_51cea4040100h152.html
Description
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 41 11 32 23 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).
#include <iostream>#include <stdio.h>#include <string.h>#include <math.h>#include <stdlib.h>using namespace std;int n;int map[502][502];bool visited[502];int match[502];bool find(int i) ///查找当前的i是否可以匹配{ int j; for(j=1;j<=n;j++) { if(map[i][j]&&!visited[j]) { visited[j]=1; if(match[j]==-1||find(match[j])) { match[j]=i; return 1; } } } return 0;}int main(){ int k,i,x,y,ans; while(~scanf("%d%d",&n,&k)) { ans=0; memset(map,0,sizeof(map)); memset(match,-1,sizeof(match)); for(i=0;i<k;i++)//对有意思的进行初始化 { scanf("%d%d",&x,&y); map[x][y]=1; } for(i=1;i<=n;i++) { memset(visited,0,sizeof(visited));//开始标记为全部没有访问 if(find(i)) ans++; } printf("%d\n",ans); } return 0;}
0 0
- Asteroids (最小覆盖)
- POJ 3041 Asteroids(最小点覆盖)
- POJ 3041 Asteroids(最小点覆盖)
- POJ 3041 Asteroids (最小点覆盖)
- POJ 3041 Asteroids(最小点覆盖)
- poj3041—Asteroids(最小点覆盖)
- POJ 3041 Asteroids(最小点覆盖)
- pku3041-Asteroids 最小点覆盖
- poj3041 Asteroids --- 最小点覆盖
- POJ3041 Asteroids(最小点覆盖)
- Poj Asteroids(最小顶点覆盖)
- 最小点覆盖 poj3041 Asteroids
- POJ3041 Asteroids (最小顶点覆盖)
- poj 题目3041 Asteroids (最小点覆盖)
- POJ 3041 Asteroids (图论-最小点覆盖)
- poj 3041 Asteroids( 最小顶点覆盖,二分图)
- poj3041 - Asteroids (二分图最小顶点覆盖)
- poj_3041 Asteroids(匈牙利算法+最小点覆盖)
- undefined、null应用场合
- golang中net/http包用法
- 通信调试工具
- nodejs使用radis
- TCP/IP协议学习笔记
- Asteroids (最小覆盖)
- spring mvc aop 拦截 附近上传
- 等比例图片缩放
- Java finally语句到底是在return之前还是之后执行?
- centos7 配置多个Tomcat
- android自定义之 5.0 风格progressBar
- .net之gridview表中数据操作
- python中多继承的问题(比较C++的多继承)
- 各种线性筛法