P1514-引水入城

  1 #include <bits/stdc++.h>
  2 #define _for(i,a,b) for(int i = (a);i < b;i ++)
  3 #define _rep(i,a,b) for(int i = (a);i > b;i --)
  4 #define INF 0x3f3f3f3f
  5 typedef long long ll;
  6 using namespace std;
  7 inline ll read()
  8 {
  9     ll ans = 0;
 10     char ch = getchar(), last = ' ';
 11     while(!isdigit(ch)) last = ch, ch = getchar();
 12     while(isdigit(ch)) ans = (ans << 1) + (ans << 3) + ch - '0', ch = getchar();
 13     if(last == '-') ans = -ans;
 14     return ans;
 15 }
 16 inline void write(ll x)
 17 {
 18     if(x < 0) x = -x, putchar('-');
 19     if(x >= 10) write(x / 10);
 20     putchar(x % 10 + '0');
 21 }
 22 struct section
 23 {
 24     int l;
 25     int r;
 26     bool operator < (section b)
 27     {
 28         if(l != b.l)
 29             return l < b.l;
 30         return r > b.r;
 31     }
 32 };
 33 
 34 int N,M;
 35 int a[503][503];
 36 section dp[503][503];
 37 bool vis[503][503];
 38 bool ok[503];
 39 int dx[] = {1,-1,0,0};
 40 int dy[] = {0,0,1,-1};
 41 
 42 bool valid(int x,int y)
 43 {
 44     return x>=1 && y>=1 && x<=N && y<=M;
 45 }
 46 
 47 void bfs()
 48 {
 49     queue<pair<int,int>> q;
 50     int arr[503][503];
 51     memset(arr,0,sizeof(arr));
 52     _for(i,1,M+1)
 53     {
 54         arr[1][i] = 1;
 55         q.push({1,i});
 56     }
 57     while(!q.empty())
 58     {
 59         pair<int,int> p = q.front();
 60         q.pop();
 61         if(p.first==N)
 62             ok[p.second] = 1;
 63         _for(i,0,4)
 64         {
 65             int nx = p.first+dx[i];
 66             int ny = p.second+dy[i];
 67             if(valid(nx,ny) && !arr[nx][ny] && a[nx][ny] < a[p.first][p.second])
 68             {
 69                 arr[nx][ny] = 1;
 70                 q.push({nx,ny});
 71             }
 72         }
 73     }
 74 }
 75 section dfs(int x,int y)
 76 {
 77     if(dp[x][y].l)
 78         return dp[x][y];
 79 
 80     section rnt;
 81     rnt.l = 0x3f3f3f3f;
 82     rnt.r = 0;
 83     _for(i,0,4)
 84     {
 85         int nx = x+dx[i];
 86         int ny = y+dy[i];
 87         if(valid(nx,ny) && !vis[nx][ny] && a[x][y]>a[nx][ny])
 88         {
 89             vis[nx][ny] = true;
 90             section t = dfs(nx,ny);
 91             vis[nx][ny] = false;
 92             rnt.l = min(rnt.l,t.l);
 93             rnt.r = max(rnt.r,t.r);
 94         }
 95     }
 96     return dp[x][y] = rnt;
 97 }
 98 int main()
 99 {
100 //    freopen("test.in","r+",stdin);
101 
102     N = read(),M = read();
103     memset(a,0x3f,sizeof(a));
104     memset(ok,0,sizeof(ok));
105     _for(i,1,N+1)
106     _for(j,1,M+1)
107     {
108         a[i][j] = read();
109         if(i==N)
110             dp[i][j].l = dp[i][j].r = j;
111     }
112 
113     _for(i,1,M+1)
114     {
115         _rep(j,i-1,-1)
116         if(a[N][j]>=a[N][j+1])
117         {
118             dp[N][i].l = j+1;
119             break;
120         }
121         _for(j,i+1,M+2)
122         if(a[N][j]>=a[N][j-1])
123         {
124             dp[N][i].r = j-1;
125             break;
126         }
127     }
128     bfs();
129     _for(i,1,M+1)
130     {
131         if(!dp[1][i].l)
132         {
133             vis[1][i] = 1;
134             dfs(1,i);
135             vis[1][i] = 0;
136         }
137     }
138 
139     int cnt = 0;
140     _for(i,1,M+1)
141     if(!ok[i])
142     {
143         cnt ++;
144     }
145     if(cnt)
146     {
147         printf("0\n%d",cnt);
148         return 0;
149     }
150 
151     sort(dp[1],dp[1]+M+1);
152 
153     int now = 1,i = 1;
154     while(i<M+1)
155     {
156         int mx = 0;
157         while(i<M+1 && dp[1][i].l<=now)
158         {
159             mx = max(mx,dp[1][i].r);
160             i ++;
161         }
162         if(dp[1][i].l==INT_MAX && now<M)
163         {
164             cnt ++;
165             break;
166         }
167         if(mx<=now-1) break;
168         now = mx+1;
169         cnt ++;
170     }
171 
172     printf("1\n%d",cnt);
173     return 0;
174 }