poj4022
模拟
利用pick公式area=on/2+in-1
计算in的时候从外围广搜所有不是in的点,再用总数减去。
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
#include <iostream> #include <cstdio> #include <cstdlib> #include <cstring> #include <algorithm> using namespace std; #define maxn 150 struct Point { int x, y; } q[maxn * maxn]; char map[maxn][maxn]; int n, m; bool vis[maxn][maxn]; int dir[4][2] = { { 1, 1 }, { 1, -1 }, { -1, 1 }, { -1, -1 } }; int dir1[4][2] = { { 1, 0 }, { 0, -1 }, { 0, 1 }, { -1, 0 } }; void input() { scanf("%d%d", &n, &m); for (int i = 0; i < n; i++) scanf("%s", map[i]); } bool out_of_bound(Point &a) { return a.x < 0 || a.y < 0 || a.x > n + 2 || a.y > m + 2; } bool ok(Point &a, Point &b) { int x = min(a.x, b.x) - 1; int y = min(a.y, b.y) - 1; if (x < 0 || y < 0 || x >= n || y >= m) return true; return map[x][y] == '.'; } bool empty(int x, int y, char ch) { if (x < 0 || y < 0 || x >= n || y >= m) return true; return map[x][y] != ch; } bool on_the_bound(Point &a) { return !empty(a.x - 2, a.y - 2, '\\') || !empty(a.x - 1, a.y - 1, '\\') || !empty(a.x - 1, a.y - 2, '/') || !empty(a.x - 2, a.y - 1, '/'); } void work() { memset(vis, 0, sizeof(vis)); vis[0][0] = true; int front, rear; front = rear = 0; Point a; a.x = a.y = 0; q[rear++] = a; int cnt = 1; while (front != rear) { a = q[front++]; for (int i = 0; i < 4; i++) { Point b; b.x = a.x + dir[i][0]; b.y = a.y + dir[i][1]; if (!out_of_bound(b) && !on_the_bound(b) && ok(a, b) && !vis[b.x][b.y]) { q[rear++] = b; vis[b.x][b.y] = true; cnt++; } b.x = a.x + dir1[i][0]; b.y = a.y + dir1[i][1]; if (!out_of_bound(b) && !on_the_bound(b) && !vis[b.x][b.y]) { q[rear++] = b; vis[b.x][b.y] = true; cnt++; } } } int on = n * m; for (int i = 0; i < n; i++) on -= count(map[i], map[i] + m, '.'); cnt += on; int in = (n + 3) * (m + 3) - cnt; int ans = on / 2 + in - 1; printf("%d\n", ans); } int main() { //freopen("t.txt", "r", stdin); input(); work(); }