分析：这里不使用直接暴力枚举的方法，而是使用最大最先算的最优算法。这里的思考方式值得学习。
方法一：使用模拟的方法，模拟寻找过程（从大到小顺序查找，找到就停止）
public class Main {
public static int a[][] = {
{1,1,1,1,1,1},
{1,0,0,0,1,1},
{1,0,0,0,1,1},
{1,0,0,0,1,1},
{1,1,1,1,1,1},
{1,0,1,1,1,1}
};
public static void main(String[] args) {
findMaxphalanx();
}
private static void findMaxphalanx() {
int N = a.length;
int n = N;
//从最大的开始找，当找到就结束
out2: while(n > 0) {
//起始点
out1: for(int i = 0; i < N; i ++) {
for(int j = 0; j < N; j ++) {
if((i + n > N ) || (j + n > N)) {
continue out1;
}
//开始模拟走圈
int nr = i + n;
int nc = j + n;
//上
for(int k = j; k < nc; k ++) {
if(a[i][k] == 0) {
continue out1;
}
}
//右
for(int k = i; k < nr; k ++) {
if(a[k][nc - 1] == 0) {
continue out1;
}
}
//下
for(int k = nc - 1; k > 0; k --) {
if(a[nr - 1][k] == 0) {
continue out1;
}
}
//左
for(int k = nr - 1; k > 0; k --) {
if(a[k][j] == 0) {
continue out1;
}
}
System.out.println(n);
break out2;
}
}
n --;
}
}
}
优化方法二：在之前用动态规划的方法先生成一个辅助查看的数组，根据数组来看是否符合
public class Main {
public static int a[][] = {
{1,1,1,1,1,1},
{1,0,0,0,1,1},
{1,0,0,0,1,1},
{1,0,0,0,1,1},
{1,0,1,1,1,1},
{1,1,0,1,1,1}
};
public static int N = a.length;
public static void main(String[] args) {
creatPhaTemp();
}
private static void creatPhaTemp() {
int temp[][][] = new int[N][N][2];
//int n = N;
//注意动态规划是从右下向左上方生成矩阵(右 + 下的和)
for(int i = N - 1; i >= 0; i --) {
for(int j = N - 1; j >= 0; j --) {
if(i == N - 1) {
if(j == N - 1) {
if(a[N - 1][j] == 1) {
temp[N - 1][j][0] = 1;
temp[N - 1][j][1] = 1;
}
else {
temp[N - 1][j][0] = 0;
temp[N - 1][j][1] = 0;
}
}
else {
if(a[N - 1][j] == 1) {
temp[i][j][0] = temp[i][j + 1][0] + 1;
temp[i][j][1] = 1;
}
else {
temp[i][j][0] = 0;
temp[i][j][1] = 0;
}
}
}
else if(j == N -1) {
if(a[i][j] == 1) {
temp[i][j][0] = 1;
temp[i][j][1] = temp[i + 1][j][1] + 1;
}
else {
temp[i][j][0] = 0;
temp[i][j][1] = 0;
}
}
else {
if(a[i][j] == 1) {
temp[i][j][0] = temp[i][j + 1][0] + 1;
temp[i][j][1] = temp[i + 1][j][1] + 1;
}
else {
temp[i][j][0] = 0;
temp[i][j][1] = 0;
}
}
}
}
for(int i = 0; i < N; i ++) {
for(int j = 0; j < N; j ++) {
System.out.print(temp[i][j][0] + "," + temp[i][j][1] + " ");
}
System.out.println();
}
for(int i = N; i >= 0; i --) {
if(check(temp , i )) return;
}
}
private static boolean check(int[][][] temp ,int n) {
for(int i = 0; i < N; i ++) {
for(int j = 0; j < N; j ++) {
int nr = i + n - 1;
int nc = j + n - 1;
if(temp[i][j][0] >= n
&&temp[i][j][1] >= n
&&temp[i][nc][1] >= n
&&temp[nr][j][0] >= n
)
{
System.out.println(n);
return true;
}
}
}
return false;
}
}