【luogu P1514 引水入城】 题解

题目链接：https://www.luogu.org/problemnew/show/P1514

// luogu-judger-enable-o2
#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#define maxn 520
#define inf 2147483647
using namespace std;
int n, m, cnt = 0, cur1 = 0, flag, ma[maxn][maxn], vis[maxn][maxn] = {0}, q[maxn];
struct cover
{
    int l,r;
}c[maxn];
int cmp(cover a, cover b)
{
    if(a.l != b.l)
    return a.l < b.l;
    else return a.r > b.r;
}
void dfs(int x, int y, int now)
{
    vis[x][y] = 1;
    if(x == n)
    {
        q[y] = 1;
        c[now].l = min(c[now].l , y);
        c[now].r = max(c[now].r , y);
    }

    if(ma[x+1][y] < ma[x][y] && x+1 <= n && vis[x+1][y] == 0) dfs(x+1,y,now);

    if(ma[x-1][y] < ma[x][y] && x-1 >= 1 && vis[x-1][y] == 0) dfs(x-1,y,now); 

    if(ma[x][y+1] < ma[x][y] && y+1 <= m && vis[x][y+1] == 0) dfs(x,y+1,now);

    if(ma[x][y-1] < ma[x][y] && y-1 >= 1 && vis[x][y-1] == 0) dfs(x,y-1,now);  
}
int main()
{
    scanf("%d%d",&n,&m);
    for(int i = 1; i <= m; i++) 
    c[i].l = inf;

    for(int i = 1; i <= n; i++)
    for(int j = 1; j <= m; j++)
    {
        scanf("%d",&ma[i][j]);
    }

    for(int i = 1; i <= m; i++)
    {
        if(ma[1][i]>=ma[1][i-1])
        dfs(1,i,i);
        memset(vis,0,sizeof(vis));
    }

    for(int i=1;i<=m;i++)
    {
        if(q[i] == 0)
        flag++;
        //cout<<q[i]<<" ";
    }
   
    sort(c+1,c+1+m,cmp);
    
    if(flag != 0)
    printf("0
%d",flag);
    else
    {
        int cur = c[1].r;
        cnt++;
        for(int i = cur; i <= m; i = cur1)
        {
            if(i == m)
            break;
            
            cnt++;
            
            for(int j = 1; c[j].l <= i+1; j++)
            cur1 = max(cur1, c[j].r);
        }
        printf("1
%d",cnt);
    }
    return 0;
}