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我枚举写的 算dfs吧 也只要204ms 为什么bfs dfs会这么大

Posted by 31201111 at 2015-02-14 14:15:31 on Problem 2965
#include <stdio.h>
#include <iostream>
#include <algorithm>
#include <string.h>
#include <queue>
#include <vector>
#include <map>
#include <math.h>
using namespace std;
typedef long long ll;
#define clr(s,x) memset(s,x,sizeof(s))
#define Max(a,b) a > b ? a : b
#define Min(a,b) a > b ? b : a
char s[4][4];
int vis[4][4];
bool press[4][4];

void init()
{
	for(int i = 0 ; i < 4; i ++)
	{
		for(int j = 0; j < 4; j++)
			scanf("%c",&s[i][j]);
		getchar();
	}
	clr(vis,0);
	clr(press,0);
}
void change(int x,int y)
{
	for(int i = 0 ; i < 4; i++)
		vis[x][i] ++;
	for(int i = 0; i < 4; i++)
		vis[i][y]++;
	vis[x][y]--;
	press[x][y] = press[x][y] ? false: true;
}
bool check()
{
	for(int i= 0 ; i < 4 ; i++)
		for(int j = 0; j < 4; j++)
			if( (s[i][j] == '+' && vis[i][j]%2 )|| (s[i][j] == '-' && !(vis[i][j]%2))) continue;
			else return false;
	/*for(int i = 0 ; i < 4; i ++)
	{
		for(int j = 0; j < 4; j++)
			cout<<vis[i][j]<<" ";
		cout<<endl;
	}*/
	return true;
}
void output()
{
	int ans = 0;
	for(int i = 0 ; i < 4; i++)
		for(int j =0 ; j < 4; j++)
			if(press[i][j]) ans++;
	printf("%d\n",ans);
	for(int i = 0 ; i < 4; i++)
		for(int j =0 ; j < 4; j++)
			if(press[i][j]) printf("%d %d\n", i+1,j+1);
}
bool solve(int x,int y)
{
	if(x == 3 && y== 3)
	{
		if(check()) return true;
		change(3,3);
		if(check()) return true;
		change(3,3);
		return false;
	}
	
	int nx,ny;
	if(y == 3) ny = 0,nx = x + 1; 
	else nx =  x, ny = y+1;

	if(solve(nx,ny)) return true;
	change(x,y);
	if(solve(nx,ny)) return true;
	change(x,y); 
	return false;
}

int main()
{
	init();
	if(solve(0,0)) output();
	else printf("wa\n");

	/*for(int i = 0; i < 4; i++)
		for(int j = 0; j < 4; j++)
			cout<<s[i][j];*/
	return 0;
}

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