首先我们注意到我们不需要保证操作数的最小化，所以我们可以将能移走的向日葵全部移走。我们可以先把奇数排全部移走。但是偶数排有可能会有两个及以上的空地，所以我们考虑用并查集来维护，对于奇数排我们要移走的格子，它的上面一个格子和左右的格子必须不在同一个连通块内。然后考虑把没有相连的连通块通过偶数排的格子连起来。
我们奇数排要讨论两次，第一次只将四周至少有一个格子是空格的格子移走。第二次再把奇数排全部连通，不然会出现不连通的错解。
然后模拟即可。
接下来是代码环节：
#include<bits/stdc++.h>
using namespace std;
struct Node {int x, y;
} f[705][705];
int t, n, m;
bool mp[705][705];
string s;
Node get_father(int x, int y) {if (f[x][y].x == x && f[x][y].y == y) {return f[x][y];} else {f[x][y] = get_father(f[x][y].x, f[x][y].y);return f[x][y];}
}
bool check(Node x, Node y) {return (x.x == y.x && x.y == y.y);
}
signed main() {ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);cin >> t;while (t --) {cin >> n >> m;for (int i = 1; i <= n; i ++) {cin >> s;s = " " + s;for (int j = 1; j <= m; j ++) {if (s[j] == 'X') {mp[i][j] = true;}}}for (int i = 0; i <= n + 5; i ++) {for (int j = 0; j <= m + 5; j ++) {f[i][j].x = i, f[i][j].y = j;}}for (int i = 1; i <= n; i ++) {for (int j = 1; j <= m; j ++) {if (mp[i][j]) {if (mp[i - 1][j]) {Node fx = get_father(i - 1, j), fy = get_father(i, j);if (!check(fx, fy)) {f[fx.x][fx.y] = fy;}}if (mp[i][j - 1]) {Node fx = get_father(i, j - 1), fy = get_father(i, j);if (!check(fx, fy)) {f[fx.x][fx.y] = fy;}}if (mp[i + 1][j]) {Node fx = get_father(i + 1, j), fy = get_father(i, j);if (!check(fx, fy)) {f[fx.x][fx.y] = fy;}}if (mp[i][j + 1]) {Node fx = get_father(i, j + 1), fy = get_father(i, j);if (!check(fx, fy)) {f[fx.x][fx.y] = fy;}}}}}for (int i = 1; i <= n; i += 2) {for (int j = 1; j <= m; j ++) {if (!mp[i][j]) {Node fnow = get_father(i, j);Node fu = get_father(i + 1, j), fd = get_father(i - 1, j), fl = get_father(i, j - 1), fr = get_father(i, j + 1);if (mp[i + 1][j] && mp[i - 1][j] && mp[i][j + 1] && mp[i][j - 1]) {if (!check(fu, fd) && !check(fu, fl) && !check(fu, fr) && !check(fd, fl) && !check(fd, fr) && !check(fl, fr)) {mp[i][j] = true;f[fu.x][fu.y] = fnow;f[fd.x][fd.y] = fnow;f[fr.x][fr.y] = fnow;f[fl.x][fl.y] = fnow;}} else if (mp[i + 1][j] && mp[i][j + 1] && mp[i - 1][j]) {if (!check(fu, fd) && !check(fu, fr) && !check(fd, fr)) {mp[i][j] = true;f[fu.x][fu.y] = fnow;f[fd.x][fd.y] = fnow;f[fr.x][fr.y] = fnow;}} else if (mp[i + 1][j] && mp[i][j + 1] && mp[i][j - 1]) {if (!check(fu, fl) && !check(fu, fr) && !check(fl, fr)) {mp[i][j] = true;f[fu.x][fu.y] = fnow;f[fr.x][fr.y] = fnow;f[fl.x][fl.y] = fnow;}} else if (mp[i + 1][j] && mp[i - 1][j] && mp[i][j - 1]) {if (!check(fu, fd) && !check(fu, fl) && !check(fd, fl)) {mp[i][j] = true;f[fu.x][fu.y] = fnow;f[fd.x][fd.y] = fnow;f[fl.x][fl.y] = fnow;}} else if (mp[i][j + 1] && mp[i - 1][j] && mp[i][j - 1]) {if (!check(fd, fl) && !check(fd, fr) && !check(fl, fr)) {mp[i][j] = true;f[fd.x][fd.y] = fnow;f[fr.x][fr.y] = fnow;f[fl.x][fl.y] = fnow;}} else if (mp[i + 1][j] && mp[i][j + 1]) {if (!check(fu, fr)) {mp[i][j] = true;f[fu.x][fu.y] = fnow;f[fr.x][fr.y] = fnow;}} else if (mp[i + 1][j] && mp[i][j - 1]) {if (!check(fu, fl)) {mp[i][j] = true;f[fu.x][fu.y] = fnow;f[fl.x][fl.y] = fnow;}} else if (mp[i - 1][j] && mp[i][j - 1]) {if (!check(fd, fl)) {mp[i][j] = true;f[fd.x][fd.y] = fnow;f[fl.x][fl.y] = fnow;}} else if (mp[i - 1][j] && mp[i][j + 1]) {if (!check(fd, fr)) {mp[i][j] = true;f[fd.x][fd.y] = fnow;f[fr.x][fr.y] = fnow;}} else if (mp[i + 1][j] && mp[i - 1][j]) {if (!check(fu, fd)) {mp[i][j] = true;f[fu.x][fu.y] = fnow;f[fd.x][fd.y] = fnow;}} else if (mp[i][j + 1] && mp[i][j - 1]) {if (!check(fl, fr)) {mp[i][j] = true;f[fl.x][fl.y] = fnow;f[fr.x][fr.y] = fnow;}} else if (mp[i + 1][j]) {mp[i][j] = true;f[fu.x][fu.y] = fnow;} else if (mp[i - 1][j]) {mp[i][j] = true;f[fd.x][fd.y] = fnow;}else if (mp[i][j + 1]) {mp[i][j] = true;f[fr.x][fr.y] = fnow;}}}}for (int i = 1; i <= n; i += 2) {for (int j = 1; j <= m; j ++) {if (!mp[i][j]) {Node fnow = get_father(i, j);Node fu = get_father(i + 1, j), fd = get_father(i - 1, j), fl = get_father(i, j - 1), fr = get_father(i, j + 1);if (mp[i + 1][j] && mp[i - 1][j] && mp[i][j + 1] && mp[i][j - 1]) {if (!check(fu, fd) && !check(fu, fl) && !check(fu, fr) && !check(fd, fl) && !check(fd, fr) && !check(fl, fr)) {mp[i][j] = true;f[fu.x][fu.y] = fnow;f[fd.x][fd.y] = fnow;f[fr.x][fr.y] = fnow;f[fl.x][fl.y] = fnow;}} else if (mp[i + 1][j] && mp[i][j + 1] && mp[i - 1][j]) {if (!check(fu, fd) && !check(fu, fr) && !check(fd, fr)) {mp[i][j] = true;f[fu.x][fu.y] = fnow;f[fd.x][fd.y] = fnow;f[fr.x][fr.y] = fnow;}} else if (mp[i + 1][j] && mp[i][j + 1] && mp[i][j - 1]) {if (!check(fu, fl) && !check(fu, fr) && !check(fl, fr)) {mp[i][j] = true;f[fu.x][fu.y] = fnow;f[fr.x][fr.y] = fnow;f[fl.x][fl.y] = fnow;}} else if (mp[i + 1][j] && mp[i - 1][j] && mp[i][j - 1]) {if (!check(fu, fd) && !check(fu, fl) && !check(fd, fl)) {mp[i][j] = true;f[fu.x][fu.y] = fnow;f[fd.x][fd.y] = fnow;f[fl.x][fl.y] = fnow;}} else if (mp[i][j + 1] && mp[i - 1][j] && mp[i][j - 1]) {if (!check(fd, fl) && !check(fd, fr) && !check(fl, fr)) {mp[i][j] = true;f[fd.x][fd.y] = fnow;f[fr.x][fr.y] = fnow;f[fl.x][fl.y] = fnow;}} else if (mp[i + 1][j] && mp[i][j + 1]) {if (!check(fu, fr)) {mp[i][j] = true;f[fu.x][fu.y] = fnow;f[fr.x][fr.y] = fnow;}} else if (mp[i + 1][j] && mp[i][j - 1]) {if (!check(fu, fl)) {mp[i][j] = true;f[fu.x][fu.y] = fnow;f[fl.x][fl.y] = fnow;}} else if (mp[i - 1][j] && mp[i][j - 1]) {if (!check(fd, fl)) {mp[i][j] = true;f[fd.x][fd.y] = fnow;f[fl.x][fl.y] = fnow;}} else if (mp[i - 1][j] && mp[i][j + 1]) {if (!check(fd, fr)) {mp[i][j] = true;f[fd.x][fd.y] = fnow;f[fr.x][fr.y] = fnow;}} else if (mp[i + 1][j] && mp[i - 1][j]) {if (!check(fu, fd)) {mp[i][j] = true;f[fu.x][fu.y] = fnow;f[fd.x][fd.y] = fnow;}} else if (mp[i][j + 1] && mp[i][j - 1]) {if (!check(fl, fr)) {mp[i][j] = true;f[fl.x][fl.y] = fnow;f[fr.x][fr.y] = fnow;}} else if (mp[i][j - 1]) {mp[i][j] = true;f[fl.x][fl.y] = fnow;} else if (mp[i + 1][j]) {mp[i][j] = true;f[fu.x][fu.y] = fnow;} else if (mp[i - 1][j]) {mp[i][j] = true;f[fd.x][fd.y] = fnow;} else if (mp[i][j + 1]) {mp[i][j] = true;f[fr.x][fr.y] = fnow;} else {mp[i][j] = true;}}}}for (int i = 2; i <= n; i += 2) {for (int j = 1; j <= m; j ++) {if (!mp[i][j]) {Node fnow = get_father(i, j);Node fu = get_father(i + 1, j), fd = get_father(i - 1, j), fl = get_father(i, j - 1), fr = get_father(i, j + 1);if (mp[i + 1][j] && mp[i - 1][j] && mp[i][j + 1] && mp[i][j - 1]) {if (!check(fu, fd) && !check(fu, fl) && !check(fu, fr) && !check(fd, fl) && !check(fd, fr) && !check(fl, fr)) {mp[i][j] = true;f[fu.x][fu.y] = fnow;f[fd.x][fd.y] = fnow;f[fr.x][fr.y] = fnow;f[fl.x][fl.y] = fnow;}} else if (mp[i + 1][j] && mp[i][j + 1] && mp[i - 1][j]) {if (!check(fu, fd) && !check(fu, fr) && !check(fd, fr)) {mp[i][j] = true;f[fu.x][fu.y] = fnow;f[fd.x][fd.y] = fnow;f[fr.x][fr.y] = fnow;}} else if (mp[i + 1][j] && mp[i][j + 1] && mp[i][j - 1]) {if (!check(fu, fl) && !check(fu, fr) && !check(fl, fr)) {mp[i][j] = true;f[fu.x][fu.y] = fnow;f[fr.x][fr.y] = fnow;f[fl.x][fl.y] = fnow;}} else if (mp[i + 1][j] && mp[i - 1][j] && mp[i][j - 1]) {if (!check(fu, fd) && !check(fu, fl) && !check(fd, fl)) {mp[i][j] = true;f[fu.x][fu.y] = fnow;f[fd.x][fd.y] = fnow;f[fl.x][fl.y] = fnow;}} else if (mp[i][j + 1] && mp[i - 1][j] && mp[i][j - 1]) {if (!check(fd, fl) && !check(fd, fr) && !check(fl, fr)) {mp[i][j] = true;f[fd.x][fd.y] = fnow;f[fr.x][fr.y] = fnow;f[fl.x][fl.y] = fnow;}} else if (mp[i + 1][j] && mp[i][j + 1]) {if (!check(fu, fr)) {mp[i][j] = true;f[fu.x][fu.y] = fnow;f[fr.x][fr.y] = fnow;}} else if (mp[i + 1][j] && mp[i][j - 1]) {if (!check(fu, fl)) {mp[i][j] = true;f[fu.x][fu.y] = fnow;f[fl.x][fl.y] = fnow;}} else if (mp[i - 1][j] && mp[i][j - 1]) {if (!check(fd, fl)) {mp[i][j] = true;f[fd.x][fd.y] = fnow;f[fl.x][fl.y] = fnow;}} else if (mp[i - 1][j] && mp[i][j + 1]) {if (!check(fd, fr)) {mp[i][j] = true;f[fd.x][fd.y] = fnow;f[fr.x][fr.y] = fnow;}} else if (mp[i + 1][j] && mp[i - 1][j]) {if (!check(fu, fd)) {mp[i][j] = true;f[fu.x][fu.y] = fnow;f[fd.x][fd.y] = fnow;}} else if (mp[i][j + 1] && mp[i][j - 1]) {if (!check(fl, fr)) {mp[i][j] = true;f[fl.x][fl.y] = fnow;f[fr.x][fr.y] = fnow;}} else if (mp[i][j - 1]) {mp[i][j] = true;f[fl.x][fl.y] = fnow;} else if (mp[i + 1][j]) {mp[i][j] = true;f[fu.x][fu.y] = fnow;} else if (mp[i - 1][j]) {mp[i][j] = true;f[fd.x][fd.y] = fnow;} else if (mp[i][j + 1]) {mp[i][j] = true;f[fr.x][fr.y] = fnow;}}}}for (int i = 1; i <= n; i ++) {for (int j = 1; j <= m; j ++) {if (mp[i][j]) {cout << "X";} else {cout << ".";}}cout << "\n";}cout << "\n";for (int i = 0; i <= n + 5; i ++) {for (int j = 0; j <= m + 5; j ++) {mp[i][j] = false;}}}return 0;
}