61.187.179.132:8080\/JudgeOnline\/showproblem<\/a>
\u6548\u4efftclsm\u795e\u725b\u76f4\u63a5\u8d34\u9898\u76ee\u4e86\u3002\u3002\u611f\u89c9\u7ed9\u6211\u672c\u6765\u5c31\u5f88\u77ed\u7684\u9898\u89e3\u51d1\u4e86\u70b9\u5b57\u56e7\u3002\u3002
\u8fd9\u9053\u9898\u76ee\u7684\u611f\u89c9\u662fSCOI2009\u6700\u6c34\u7684\uff0c\u679a\u4e3e\u6bcf\u4e2a\u8d77\u70b9\uff0c\u76f4\u63a5BFS\uff0c\u590d\u6742\u5ea6\u662fO(n^2m^2)\u7684\uff0c\u540c\u65f6\u53ef\u4ee5\u89c4\u5b9a\u7ec8\u70b9\u7684\u6a2a\u5750\u6807\u5927\u4e8e\u8d77\u70b9\u3002\u3002\u51cf\u5c11\u4e00\u534a\u641c\u7d22\u91cf\u3002\u3002
BFS\u7684\u65f6\u5019\u6ce8\u610f\u8fb9\u6743\u53ef\u4ee5\u662f1\u4e5f\u53ef\u4ee5\u662f0\uff0c\u90a3\u4e48\u7528\u4e00\u4e2adeque\u4ee3\u66ffqueue\uff0c\u9047\u52300\u8fb9\u5c31\u653e\u8fdb\u5bf9\u9996\uff0c\u5426\u5219\u653e\u8fdb\u961f\u5c3e\u5c31OK\u4e86\u3002\u3002
\u6211\u4eceqzc\u795e\u725b\u7684\u4ee3\u7801\u4e2d\u770b\u5230define\u662f\u53ef\u4ee5\u653e\u5728\u51fd\u6570\u4e2d\u7684\uff0c\u800c\u4e14\u53ef\u4ee5\u7528#undef\u7ed9\u53d6\u6d88\u6389\uff0c\u592aorz\u4e86\u3002\u3002
Code\uff1a<\/p>\n#include<cstdio>
#include<iostream>
#include<algorithm>
#include<string>
#include<vector>
#include<cstring>
#include<deque>
#include<cmath>
#define rep(i,n) for(int i=0;i<n;i++)
#define pb push_back
#define pf push_front
using namespace std;
typedef pair<int,int> ii;
const int inf=~0U>>1,maxn=30;
int n,m,T;
double ans=0;
bool Map[maxn][maxn];
const int di[]={1,0,-1,0},dj[]={0,1,0,-1};
void bfs(int x,int y)
{
static bool vis[maxn][maxn];
static int dist[maxn][maxn];
memset(vis,0,sizeof(vis));
deque<ii> Q;dist[x][y]=Map[x][y];
vis[x][y]=true;Q.pb(ii(x,y));
#define legal(i,j) (i>=x&&i<n&&j>=0&&j<m&&!vis[i][j])
#define A first
#define B second
double tx,ty;
while(Q.size())
{
ii t=Q.front();int cost=dist[t.A][t.B],xx,yy;Q.pop_front();
if(cost>T)break;
tx=t.A-x;ty=t.B-y;
ans=max(ans,tx*tx+ty*ty);
rep(d,4)
{
xx=t.A+di[d];
yy=t.B+dj[d];
if(legal(xx,yy))
{
if(Map[xx][yy])
Q.pb(ii(xx,yy)),dist[xx][yy]=cost+1;
else
Q.pf(ii(xx,yy)),dist[xx][yy]=cost;
vis[xx][yy]=true;
}
}
}
#undef legal
#undef A
#undef B
}
int main()
{
\/\/freopen("in","r",stdin);
cin>>n>>m>>T;char x;
rep(i,n)rep(j,m)cin>>x,Map[i][j]=x==’1′;
rep(i,n)rep(j,m)bfs(i,j);
ans=sqrt(ans);
printf("%0.6lf",ans);
}<\/p>\n","protected":false},"excerpt":{"rendered":"
[SCOI2009]\u6700\u957f\u8ddd\u79bb Time Limit:10000MS Memory Limit:165536KTotal Submit:25 Accepted:16 Case Time Limit:1000MS Description windy\u6709\u4e00\u5757\u77e9\u5f62\u571f\u5730\uff0c\u88ab\u5206\u4e3a N*M \u5757 1*1 \u7684\u5c0f\u683c\u5b50\u3002 \u6709\u7684\u683c\u5b50\u542b\u6709\u969c\u788d\u7269\u3002 \u5982\u679c\u4ece\u683c\u5b50A\u53ef\u4ee5\u8d70\u5230\u683c\u5b50B\uff0c\u90a3\u4e48\u4e24\u4e2a\u683c\u5b50\u7684\u8ddd\u79bb\u5c31\u4e3a\u4e24\u4e2a\u683c\u5b50\u4e2d\u5fc3\u7684\u6b27\u51e0\u91cc\u5fb7\u8ddd\u79bb\u3002 \u5982\u679c\u4ece\u683c\u5b50A\u4e0d\u53ef\u4ee5\u8d70\u5230\u683c\u5b50B\uff0c\u5c31\u6ca1\u6709\u8ddd\u79bb\u3002 \u5982\u679c\u683c\u5b50X\u548c\u683c\u5b50Y\u6709\u516c\u5171\u8fb9\uff0c\u5e76\u4e14X\u548cY\u5747\u4e0d\u542b\u6709\u969c\u788d\u7269\uff0c\u5c31\u53ef\u4ee5\u4eceX\u8d70\u5230Y\u3002 \u5982\u679cwindy\u53ef\u4ee5\u79fb\u8d70T\u5757\u969c\u788d\u7269\uff0c\u6c42\u6240\u6709\u683c\u5b50\u95f4\u7684\u6700\u5927\u8ddd\u79bb\u3002 \u4fdd\u8bc1\u79fb\u8d70T\u5757\u969c\u788d\u7269\u4ee5\u540e\uff0c\u81f3\u5c11\u6709\u4e00\u4e2a\u683c\u5b50\u4e0d\u542b\u6709\u969c\u788d\u7269\u3002 Input \u8f93\u5165\u6587\u4ef6maxlength.in\u7b2c\u4e00\u884c\u5305\u542b\u4e09\u4e2a\u6574\u6570\uff0cN M T\u3002 \u63a5\u4e0b\u6765\u6709N\u884c\uff0c\u6bcf\u884c\u4e00\u4e2a\u957f\u5ea6\u4e3aM\u7684\u5b57\u7b26\u4e32\uff0c’0’\u8868\u793a\u7a7a\u683c\u5b50\uff0c’1’\u8868\u793a\u8be5\u683c\u5b50\u542b\u6709\u969c\u788d\u7269\u3002 Output \u8f93\u51fa\u6587\u4ef6maxlength.out\u5305\u542b\u4e00\u4e2a\u6d6e\u70b9\u6570\uff0c\u4fdd\u75596\u4f4d\u5c0f\u6570\u3002 Sample Input \u3010\u8f93\u5165\u6837\u4f8b\u4e00\u30113 3 0001001110 \u3010\u8f93\u5165\u6837\u4f8b\u4e8c\u30114 3 0001001011000 \u3010\u8f93\u5165\u6837\u4f8b\u4e09\u30113 3 1001001001 Sample Output \u3010\u8f93\u51fa\u6837\u4f8b\u4e00\u30111.414214 \u3010\u8f93\u51fa\u6837\u4f8b\u4e8c\u30113.605551 \u3010\u8f93\u51fa\u6837\u4f8b\u4e09\u30112.828427 Hint 20%\u7684\u6570\u636e\uff0c\u6ee1\u8db3 1 <= N,M <= 30 \uff1b 0 <= […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[10],"tags":[],"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=\/wp\/v2\/posts\/161"}],"collection":[{"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=161"}],"version-history":[{"count":0,"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=\/wp\/v2\/posts\/161\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=161"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=161"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.shuizilong.com\/wjmzbmr\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=161"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}