NOIP 考前 队列复习

 1  
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <iostream>
 5 #include <algorithm>
 6 #define M 2020
 7 using namespace std;
 8 int n,k,a[M][M];
 9 long long sum[M][M];
10 long long Get_Sum(int x1,int y1,int x2,int y2)
11 {
12     return sum[x2][y2]-sum[x1-1][y2]-sum[x2][y1-1]+sum[x1-1][y1-1];
13 }
14 void Output(int x1,int y1,int x2,int y2)
15 {
16     while( Get_Sum(x1,y1,x2,y2)>k*2 )
17     {
18         if(x1==x2)
19             y2--;
20         else
21         {
22             if( Get_Sum(x1+1,y1,x2,y2)>=k )
23                 x1++;
24             else
25                 x2--;
26         }
27     }
28     printf("%d %d %d %d\n",y1,x1,y2,x2);
29     exit(0);
30 }
31 void Monotonous_Stack(int base,int h[])
32 {
33     static int stack[M],top;
34     static int l[M],r[M];
35     int i;
36  
37     for(top=0,i=1;i<=n+1;i++)
38     {
39         while( top && h[stack[top]]>h[i] )
40             r[stack[top--]]=i-1;
41         stack[++top]=i;
42     }
43     for(top=0,i=n;i>=0;i--)
44     {
45         while( top && h[stack[top]]>h[i] )
46             l[stack[top--]]=i+1;
47         stack[++top]=i;
48     }
49     for(i=1;i<=n;i++)
50         if(h[i])
51         {
52             long long temp=Get_Sum(base-h[i]+1,l[i],base,r[i]);
53             if( temp>=k )
54                 Output(base-h[i]+1,l[i],base,r[i]);
55         }
56 }
57 int main()
58 {
59     int i,j;
60     cin>>k>>n;
61     for(i=1;i<=n;i++)
62         for(j=1;j<=n;j++)
63         {
64             scanf("%d",&a[i][j]);
65             if( a[i][j]>=k && a[i][j]<=k*2 )
66             {
67                 printf("%d %d %d %d\n",j,i,j,i);
68                 return 0;
69             }
70             sum[i][j]=sum[i-1][j]+sum[i][j-1]-sum[i-1][j-1]+a[i][j];
71         }
72     static int h[M];
73     for(i=1;i<=n;i++)
74     {
75         for(j=1;j<=n;j++)
76             h[j]=a[i][j]>k*2?0:h[j]+1;
77         Monotonous_Stack(i,h);
78     }
79     puts("NIE");
80     return 0;
81 }