第一种方法：
#include#include #include #include #include #define CLR(a, b) memset(a, b, sizeof(a)) using namespace std; typedef long long LL; const int N = 5050; struct Point { int x, y; bool operator < (const Point& rhs) const { return x < rhs.x || (x == rhs.x && y < rhs.y); } }p[N]; bool vis[2][2], hav[N * 6]; int n, x, y, l, w; int solve() { int ret = 0, u, d = 0, s; for(int i = 0; i <= w; i ++) { if(vis[hav[i]]) { ret = max(ret, l * (i - d)); d = i; } } for(int i = 0; i < n; i ++) { u = w, d = 0;s = i; while(p[s].x == p[i].x && s < n) s ++; for(int j = s; j < n; j ++) { ret = max(ret, (u - d) * (p[j].x - p[i].x)); if(p[j].y > p[i].y && p[j].y < u) u = p[j].y; else if(p[j].y <= p[i].y && p[j].y > d)d = p[j].y; } ret = max(ret, (u - d) * (l - p[i].x)); } for(int i = n - 1; i >= 0; i --) { u = w, d = 0;s = i; while(p[s].x == p[i].x && s >= 0) s --; for(int j = s; j >= 0; j --) { ret = max(ret, (u - d) * (p[i].x - p[j].x)); if(p[j].y > p[i].y && p[j].y < u) u = p[j].y; else if(p[j].y <= p[i].y && p[j].y > d)d = p[j].y; } ret = max(ret, (u - d) * p[i].x); } return ret; } int main() { //freopen("input.txt", "r", stdin); while(~scanf("%d%d", &l, &w)) { scanf("%d", &n);CLR(vis, 0); CLR(hav, 0); for(int i = 0; i < n; i ++) { scanf("%d%d", &x, &y); p[i].x = x, p[i].y = y; if(x == 0 && y == 0) vis[0][0] = 1; if(x == l && y == 0) vis[1][0] = 1; if(x == 0 && y == w) vis[0][1] = 1; if(x == l && y == w) vis[1][1] = 1; } for(int i = 0; i < 2; i ++) for(int j = 0; j < 2; j ++) if(!vis[i][j]) { p[n].x = i * l; p[n ++].y = j * w; } sort(p, p + n); printf("%d\n", solve()); } }