题解 | #疯牛病II#

此题核心是在没传染的牛身边找被传染的牛
找到了就传染，没找到病牛但有健康牛则失败，没健康牛则成功

import java.util.*;


public class Solution {

    static List<Integer> timeList = new ArrayList<>();
    static int maxTime = -1;
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param pasture int整型二维数组 
     * @return int整型
     */
    public int healthyCowsII (int[][] pasture) {
        // write code here
        
        trancefom(pasture, 0);
        
        return maxTime;
    }

    public void trancefom(int[][] pasture, int index) {
        int[][] newPasture = new int[pasture.length][pasture.length];
        for(int i = 0; i < pasture.length; i ++) {
            newPasture[i] = Arrays.copyOf(pasture[i], pasture.length);
        }
    
        // 查找健康牛有没有病牛在旁边
        boolean hasTrance = false;
        boolean haHealth = false;
        for(int i = 0; i < newPasture.length; i ++) {
            for(int k = 0; k < newPasture.length; k ++) {
                if (newPasture[i][k] == 1) {
                      int X1 = i -1;
                      int X2 = i +1;
                      int Y1 = k -1;
                      int Y2 = k +1;
                      haHealth = true;
                    if (X1 >= 0) {
                        if (pasture[X1][k] == 2) {
                            newPasture[i][k] = 2;
                            hasTrance = true;
                        }
                    }
                    if (X2 < pasture.length) {
                        if (pasture[X2][k] == 2) {
                            newPasture[i][k] = 2;
                            hasTrance = true;
                        }
                    }
                    if (Y1 >= 0) {
                        if (pasture[i][Y1] == 2) {
                            newPasture[i][k] = 2;
                            hasTrance = true;
                        }
                    }
                    if (Y2 < pasture.length) {
                        if (newPasture[i][Y2] == 2) {
                            newPasture[i][k] = 2;
                            hasTrance = true;
                        }
                    }
                }
            }
        }
        // 则本轮结束
        // 没有健康的牛
        if (!haHealth) {
            if (maxTime != -1) {
                maxTime = maxTime > index ? index:maxTime;
            } else {
                maxTime = index;
            }
            return;
        }
        // 有健康牛但没有被传染
        if (haHealth && !hasTrance) {
            return;
        }
        if (haHealth && hasTrance) {
            trancefom(newPasture, index +1);
        }
    }

}