剪格子

package 搜索;


import java.util.Scanner;


public class 剪格子 {
static int arr[][];
static int n;
static int m;
static int result;
static int x[] = { 1, 0, -1, 0 };
static int y[] = { 0, 1, 0, -1 };
static int half;
static boolean[][] flag;


public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
m = sc.nextInt();
n = sc.nextInt();
result = n * m;
arr = new int[n][m];
flag = new boolean[n][m];
int sum = 0;
int max = 0;
for (int i = 0; i < n; i++) {
for (int j = 0; j < m; j++) {
arr[i][j] = sc.nextInt();
sum += arr[i][j];
if (arr[i][j] > max)
max = arr[i][j];
}
}


half = sum / 2;
if (half * 2 != sum || max > half) {
System.out.println(0);
return;
}
f();
}


private static void f() {
for (int i = 0; i < n; i++)
for (int j = 0; j < m; j++) {
dfs(i, j, 1);
}
System.out.println(result == n * m ? 0 : result);
}


private static void dfs(int row, int col, int count) {
flag[row][col] = true;
half -= arr[row][col];
if (half == 0) {
int re = count;
if (!flag[0][0]) {
re = n * m - re;
if (re < result)
result = re;
} else if (flag[0][0]) {
if (re < result)
result = re;
}
} else {
for (int i = 0; i < 4; i++) {
int xx = row + x[i];
int yy = col + y[i];
if (check(xx, yy)) {
continue;
}
dfs(xx, yy, count + 1);
}
}
flag[row][col] = false;
half += arr[row][col];


}


private static boolean check(int xx, int yy) {
return xx < 0 || xx >= n || yy < 0 || yy >= m || flag[xx][yy]
|| half - arr[xx][yy] < 0;
}
}