luogu 4554 小明的游戏

分析

没事干不要乱建图

隔壁白银莲花池是因为不能有零环才重新建图的

这道题，直接01走起就好

听说是什么01BFS

0插队首，1插队尾，时间复杂度，可以自己算，也可以造个大数据

莫名RE，一直以为应该是TLE来着

代码

  1 /**************************
  2 User:Mandy.H.Y
  3 Language:c++
  4 Problem:luogu4554
  5 Algorithm: 
  6 Date:2019.9.4
  7 **************************/
  8 
  9 #include<bits/stdc++.h>
 10 
 11 using namespace std;
 12 
 13 const int maxn = 505;
 14 const int maxm = 1e6 + 5;
 15 
 16 int n,m;
 17 int dis[maxn][maxn];
 18 char a[maxn][maxn];
 19 bool vis[maxn][maxn];
 20 
 21 struct Node{
 22     int x,y;
 23     Node(int _x = 0,int _y = 0):x(_x),y(_y){}
 24 }q[300005],s,t;
 25 int l,r;
 26 
 27 int dx[5] = {0,0,1,-1};
 28 int dy[5] = {1,-1,0,0};
 29 
 30 template<class T>inline void read(T &x){
 31     x = 0;bool flag = 0;char ch = getchar();
 32     while(!isdigit(ch)) flag |= ch == '-',ch = getchar();
 33     while(isdigit(ch)) x = (x << 1) + (x << 3) + (ch ^ 48),ch = getchar();
 34     if(flag) x = -x;
 35 }
 36 
 37 template<class T>void putch(const T x){
 38     if(x > 9) putch(x / 10);
 39     putchar(x % 10 | 48);
 40 }
 41 
 42 template<class T>void put(const T x){
 43     if(x < 0) putchar('-'),putch(-x);
 44     else putch(x);
 45 }
 46 
 47 void file(){
 48     freopen("4554.in","r",stdin);
 49 //    freopen("4554.out","w",stdout);
 50 }
 51 
 52 void readdata(){
 53     for(int i = 0;i < n; ++ i) scanf("%s",a[i]);
 54     read(s.x);read(s.y);
 55     read(t.x);read(t.y);
 56 }
 57 
 58 void SPFA(){
 59     memset(vis,0,sizeof(vis));
 60     memset(dis,0x3f3f3f3f,sizeof(dis));
 61     l = r = 0;
 62     q[r++] = s;
 63     dis[s.x][s.y] = 0;
 64     while(l != r){
 65         Node u = q[l];
 66         int x = u.x;
 67         int y = u.y;
 68         ++l;
 69         l = l % 260000;
 70         int rr = (r - 1 + 260000) % 260000;
 71         if(l != r && dis[q[l].x][q[l].y] > dis[q[rr].x][q[rr].y]) swap(q[l],q[rr]);
 72         vis[x][y] = 0;
 73         for(int i = 0;i < 4; ++ i){
 74             int nx = x + dx[i];
 75             int ny = y + dy[i];
 76             if(nx >= n || ny >= m || nx < 0 || ny < 0) continue;
 77             int w;
 78             if(a[x][y] == a[nx][ny]) w = 0;
 79             else w = 1;
 80             if(dis[nx][ny] > dis[x][y] + w){
 81                 dis[nx][ny] = dis[x][y] + w;
 82                 if(!vis[nx][ny]){
 83                     q[r++] = Node(nx,ny);
 84                     vis[nx][ny] = 1;
 85                     r %= 260000;
 86                     int rr = (r - 1 + 260000) % 260000;
 87                     if(l != r && dis[q[l].x][q[l].y] > dis[q[rr].x][q[rr].y]) swap(q[l],q[rr]);
 88                 }
 89                 
 90             }
 91         }
 92     }
 93 }
 94 
 95 void work(){
 96     
 97     SPFA();
 98     
 99     put(dis[t.x][t.y]);
100     putchar('\n');
101 }
102 
103 int main(){
104 //    file();
105     while(1){
106         scanf("%d%d",&n,&m);
107         if((!n) && (!m)) break;
108         readdata();
109         work();
110     }
111     return 0;
112 }
View Code

 

posted @ 2019-09-04 16:46  Mandy_H_Y  阅读(170)  评论(0)  编辑  收藏  举报