UVA 1589 Xiangqi

题目链接：https://vjudge.net/problem/UVA-1589

题目翻译摘自《算法禁赛入门经典》

题目大意

　　考虑一个象棋残局，其中红方有 n（2 ≤ n ≤ 7）个棋子，黑方只有一个将。红方除了有一个 帅（G）之外还有3种可能的棋子：车（R），马（H），炮（C），并且需要考虑“蹩马 腿”与将和帅不能照面（将、帅如果同在一条直线上，中间又不隔着任何棋 子的情况下，走子的一方获胜）的规则。

　　输入所有棋子的位置，保证局面合法并且红方已经将军。你的任务是判断红方是否已经 把黑方将死。

分析

　　略。

代码如下

#include <bits/stdc++.h>
using namespace std;
 
#define INIT() ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define Rep(i,n) for (int i = 0; i < (n); ++i)
#define For(i,s,t) for (int i = (s); i <= (t); ++i)
#define rFor(i,t,s) for (int i = (t); i >= (s); --i)
#define ForLL(i, s, t) for (LL i = LL(s); i <= LL(t); ++i)
#define rForLL(i, t, s) for (LL i = LL(t); i >= LL(s); --i)
#define foreach(i,c) for (__typeof(c.begin()) i = c.begin(); i != c.end(); ++i)
#define rforeach(i,c) for (__typeof(c.rbegin()) i = c.rbegin(); i != c.rend(); ++i)
 
#define pr(x) cout << #x << " = " << x << "  "
#define prln(x) cout << #x << " = " << x << endl
 
#define LOWBIT(x) ((x)&(-x))
 
#define ALL(x) x.begin(),x.end()
#define INS(x) inserter(x,x.begin())
 
#define ms0(a) memset(a,0,sizeof(a))
#define msI(a) memset(a,inf,sizeof(a))
#define msM(a) memset(a,-1,sizeof(a))

#define MP make_pair
#define PB push_back
#define ft first
#define sd second
 
template<typename T1, typename T2>
istream &operator>>(istream &in, pair<T1, T2> &p) {
    in >> p.first >> p.second;
    return in;
}
 
template<typename T>
istream &operator>>(istream &in, vector<T> &v) {
    for (auto &x: v)
        in >> x;
    return in;
}
 
template<typename T1, typename T2>
ostream &operator<<(ostream &out, const std::pair<T1, T2> &p) {
    out << "[" << p.first << ", " << p.second << "]" << "
";
    return out;
}

inline int gc(){
    static const int BUF = 1e7;
    static char buf[BUF], *bg = buf + BUF, *ed = bg;
    
    if(bg == ed) fread(bg = buf, 1, BUF, stdin);
    return *bg++;
} 

inline int ri(){
    int x = 0, f = 1, c = gc();
    for(; c<48||c>57; f = c=='-'?-1:f, c=gc());
    for(; c>47&&c<58; x = x*10 + c - 48, c=gc());
    return x*f;
}

template<class T>
inline string toString(T x) {
    ostringstream sout;
    sout << x;
    return sout.str();
}
 
typedef long long LL;
typedef unsigned long long uLL;
typedef pair< double, double > PDD;
typedef pair< int, int > PII;
typedef pair< int, PII > PIPII;
typedef pair< string, int > PSI;
typedef pair< int, PSI > PIPSI;
typedef set< int > SI;
typedef set< PII > SPII;
typedef vector< int > VI;
typedef vector< VI > VVI;
typedef vector< PII > VPII;
typedef map< int, int > MII;
typedef map< int, string > MIS;
typedef map< int, PII > MIPII;
typedef map< PII, int > MPIII;
typedef map< string, int > MSI;
typedef map< string, string > MSS;
typedef map< PII, string > MPIIS;
typedef map< PII, PII > MPIIPII;
typedef multimap< int, int > MMII;
typedef multimap< string, int > MMSI;
//typedef unordered_map< int, int > uMII;
typedef pair< LL, LL > PLL;
typedef vector< LL > VL;
typedef vector< VL > VVL;
typedef priority_queue< int > PQIMax;
typedef priority_queue< int, VI, greater< int > > PQIMin;
const double EPS = 1e-6;
const LL inf = 0x7fffffff;
const LL infLL = 0x7fffffffffffffffLL;
const LL mod = 1e9 + 7;
const int maxN = 1e4 + 7;
const LL ONE = 1;
const LL evenBits = 0xaaaaaaaaaaaaaaaa;
const LL oddBits = 0x5555555555555555;

struct Point{
    int X, Y;
    
    Point() {}
    Point(int x, int y) : X(x), Y(y) {}
    
    bool between(const Point &x, const Point &y) {
        if(x.X == y.X && X == x.X && Y > min(x.Y, y.Y) && Y < max(x.Y, y.Y)) return true;
        if(x.Y == y.Y && Y == x.Y && X > min(x.X, y.X) && X < max(x.X, y.X)) return true;
        return false;
    }
    
    Point operator+ (const Point &x) const {
        return Point(X + x.X, Y + x.Y);
    }
    
    bool operator== (const Point &x) const {
        return X == x.X && Y == x.Y;
    }
    
    bool operator!= (const Point &x) const {
        return !(*this == x);
    }
};

istream &operator>> (istream &in, Point &x) {
    in >> x.X >> x.Y;
    return in;
}

ostream &operator<< (ostream &out, const Point &x) {
    out << "(" << x.X << ", " << x.Y << ")" << endl;
    return out;
}

int N;
Point BGpos, RGpos; 
multimap< string, Point > R;
Point d[] = {Point(-1, 0), Point(0, 1), Point(1, 0), Point(0, -1)};
Point h[] = {Point(-2, -1), Point(-2, 1), Point(-1, 2), Point(1, 2), Point(2, 1), Point(2, -1), Point(1, -2), Point(-1, -2)};
bool ans;

bool checkR(Point x, Point y) {
    if(x.X != y.X && x.Y != y.Y) return false;
    foreach(i, R) if(i->sd != x && i->sd != y && i->sd.between(x, y)) return false;
    return true;
}

bool checkG(Point x, Point y) {
    return checkR(x, y);
}

bool checkH(Point x, Point y) {
    int vis[4] = {0};
    Rep(i, 4) foreach(j, R) if(x + d[i] == j->sd) vis[i] = 1;
    Rep(i, 8) if(!vis[i >> 1] && x + h[i] == y) return true;
    return false;
}

bool checkC(Point x, Point y) {
    int cnt = 0;
    foreach(i, R) if(i->sd != x && i->sd != y && i->sd.between(x, y)) ++cnt;
    return cnt == 1;
}

MSI f_id = {MP("G", 0), MP("R", 1), MP("H", 2), MP("C", 3)};
bool (*func[4])(Point, Point) = {checkG, checkR, checkH, checkC};

bool ischeck(Point x) {
    if(!(x.Y < 7 && x.Y > 3 && x.X > 0 && x.X < 4)) return true;
    // 枚举每个棋子能不能将死对面 
    foreach(i, R) if(i->sd != x && func[f_id[i->ft]](i->sd, x)) return true;
    return false;
}

int main(){
    //freopen("MyOutput.txt","w",stdout);
    //freopen("input.txt","r",stdin);
    INIT();
    while(cin >> N >> BGpos) {
        if(!N) break;
        ans = true;
        R.clear();
        Rep(i, N) {
            string tmp;
            Point t;
            cin >> tmp >> t;
            R.insert(MP(tmp, t));
            if(tmp == "G") RGpos = t;
        }
        
        if(checkG(RGpos, BGpos)) { // 将帅照面 
            cout << "NO" << endl;
            continue;
        }
        Rep(i, 4) {
            if(!ischeck(BGpos + d[i])) {
                ans = false;
                break;
            }
        }
        if(ans) cout << "YES" << endl;
        else cout << "NO" << endl;
    }
    return 0;
}