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minMalware.java
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53 lines (52 loc) · 1.9 KB
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import java.util.*;
public class minMalware {
public static void main(String[] args){
int[][] graph = {{1,1,0}, {1,1,0}, {0,0,1}};
int[] initial = {0, 1};
System.out.println(minMalwareSpread(graph, initial));
}
/*
思路非常strightforward: 对于initial里面的每个元素，都做一遍BFS遍历graph。记录在去除此元素的情况下，还能传染几个。
返回传染最少的那个
*/
public static int minMalwareSpread(int[][] graph, int[] initial) {
Arrays.sort(initial);
int min = graph.length;
int res = -1;
for(int i = 0; i < initial.length; i++){
int infected = spread(graph, initial, initial[i]);
if(infected < min){
res = initial[i];
min = infected;
}
}
return res;
}
// helper function: 传染
public static int spread(int[][] graph, int[] initial, int target){
boolean[] visied = new boolean[graph.length];
int sum = 0;
for(int i = 0; i < initial.length; i++){
if(initial[i] == target || visied[initial[i]]) continue;
Queue<Integer> queue = new LinkedList<>();
// 关键在于这里的细节：
// 是add的时候标成visited，而不是remove的时候。不然会重复加进元素进去
queue.add(initial[i]);
visied[initial[i]] = true;
sum ++;
while(!queue.isEmpty()){
int k = queue.remove();
// traverse its neighbors
for(int j = 0; j < graph[k].length; j++){
if(j == target) continue;
if(graph[k][j] == 1 && !visied[j]){
visied[j] = true;
queue.add(j);
sum ++;
}
}
}
}
return sum;
}
}