Rectangle Matrix (0)

int P[MX][MX];
int lrc(int N,int M){
    static int U[MX][MX],L[MX][MX],R[MX][MX];
    int r(0);
    F(N){
        int lo(-1),ro(M);
        FF(M)if(P[i][j])
            U[i][j]=L[i][j]=0,lo=j;
        else U[i][j]=!i?1:U[i-1][j]+1,L[i][j]=!i?lo+1:max(L[i-1][j],lo+1);
        for(int j(M-1);~j;--j)
            if(P[i][j])R[i][j]=N,ro=j;
            else R[i][j]=!i?ro-1:min(R[i-1][j],ro-1)
               ,r=max(r,U[i][j]*(R[i][j]-L[i][j]+1));
    }
    return r;
}