Topcoder SRM646 div1 600 bfs+剪枝

来源：互联网发布：剑网三的软件编辑：程序博客网时间：2024/05/27 20:35
因为只有47个blocks，所以现在小范围内，即在-50 <= x <= 50,-50 <= y <= 50内进行bfs，之后尽量让点向右走，记录最大值。
#include <algorithm>#include <iostream>#include <cstring>#include <cstdlib>#include <cstdio>#include <queue>#include <cmath>#include <stack>#include <map>#include <ctime>#include <iomanip>#pragma comment(linker,"/STACK:1024000000");#define EPS (1e-6)#define LL long long#define ULL unsigned long long#define _LL __int64#define INF 0x3f3f3f3f#define Mod 1000000007using namespace std;struct P{    int x,y,k;};queue<P> q;map<pair<int,int>,int> M;class TheGridDivOne{public :    int find(vector <int> x, vector <int> y, int k)    {        q.push((P){0,0,0});        M.insert( pair<pair<int,int>,int> (pair<int,int>(0,0),0));        P f,s;        int i , n;        n = x.size();        int Max = 0;        map<pair<int,int>,int>::iterator it;        while(q.empty() == false)        {            f = q.front();            q.pop();            if(k-f.k+f.x <= Max)                continue;            Max = max(Max,f.x);            it = M.find(pair<int,int>(f.x,f.y));                  if(it->second < f.k)                continue;            int U = Mod,D = -Mod,L = -Mod,R = Mod;            s = f;            for(i = 0; i < n; ++i)            {                if(x[i] == s.x && y[i] > s.y)                    U = min(U,y[i]);                if(x[i] == s.x && y[i] < s.y)                    D = max(D,y[i]);                if(y[i] == s.y && x[i] > s.x)                    R = min(R,x[i]);                if(y[i] == s.y && x[i] < s.x)                    L = max(L,x[i]);            }            s.y = f.y,s.x = min(f.x+k-f.k,R-1),s.k = f.k+s.x-f.x;            it = M.find(pair<int,int>(s.x,s.y));            if(it == M.end())            {                q.push(s);                M.insert( pair<pair<int,int>,int> (pair<int,int>(s.x,s.y),s.k));            }            else if(it->second > s.k)            {                q.push(s);                it->second = s.k;            }            for(i = f.x-1; i > max(f.x-2,L); --i)            {                s.x = i,s.y = f.y,s.k = f.k + f.x-i;                it = M.find( pair<int,int>(s.x,s.y) );                if(s.k > k)                    break;                if(it == M.end())                {                    M.insert( pair<pair<int,int>,int> (pair<int,int>(s.x,s.y),s.k));                    q.push(s);                }                else if(it->second > s.k)                {                    it->second = s.k;                    q.push(s);                }            }            for(i = f.y+1; i < min(f.y+2,U); ++i)            {                s.x = f.x,s.y = i,s.k = f.k + i-f.y;                if(s.k > k)                    break;                it = M.find( pair<int,int>(s.x,s.y));                if(it == M.end())                {                    M.insert( pair<pair<int,int>,int> (pair<int,int>(s.x,s.y),s.k));                    q.push(s);                }                else if(it->second > s.k)                {                    it->second = s.k;                    q.push(s);                }            }            for(i = f.y-1; i > max(f.y-2,D); --i)            {                s.x = f.x,s.y = i,s.k = f.k + f.y-i;                if(s.k > k)                    break;                it = M.find( pair<int,int>(s.x,s.y));                if(it == M.end())                {                    M.insert( pair<pair<int,int>,int> (pair<int,int>(s.x,s.y),s.k));                    q.push(s);                }                else if(it->second > s.k)                {                    it->second = s.k;                    q.push(s);                }            }            if(f.k <= 50)            {                for(i = f.x+1; i < min(f.x+2,R); ++i)                {                    s.x = i,s.y = f.y,s.k = f.k + i-f.x;                    it = M.find( pair<int,int>(s.x,s.y) );                    if(s.k > k)                        break;                    if(it == M.end())                    {                        M.insert( pair<pair<int,int>,int> (pair<int,int>(s.x,s.y),s.k));                        q.push(s);                    }                    else if(it->second > s.k)                    {                        it->second = s.k;                        q.push(s);                    }                }            }        }        return Max;    }};
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