BZOJ 1047 [HAOI2007]理想的正方形

  1 #include <deque>
  2 #include <cstdio>
  3 #include <cstring>
  4 #include <algorithm>
  5 
  6 using namespace std;
  7 
  8 void Get_Val(int &Ret)
  9 {
 10     Ret = 0;
 11     char ch;
 12     while ((ch = getchar()), (ch > ‘9‘ || ch < ‘0‘))
 13         ;
 14     do
 15     {
 16         (Ret *= 10) += ch - ‘0‘;
 17     }
 18     while ((ch = getchar()), (ch >= ‘0‘ && ch <= ‘9‘));
 19 }
 20 
 21 const size_t Max_AB(1050);
 22 
 23 int A, B;
 24 int N;
 25 int Value[Max_AB][Max_AB];
 26 
 27 int colmax[Max_AB][Max_AB], rowmax[Max_AB][Max_AB];
 28 int colmin[Max_AB][Max_AB], rowmin[Max_AB][Max_AB];
 29 
 30 void init()
 31 {
 32     Get_Val(A), Get_Val(B), Get_Val(N);
 33     for (int i = 1;i <= A;++i)
 34         for (int j = 1;j <= B;++j)
 35             Get_Val(Value[i][j]);
 36 }
 37 
 38 struct node
 39 {
 40     node(const int &a = 0, const int &b = 0) : Number(a), Value(b) {}
 41     int Number;
 42     int Value;
 43 };
 44 
 45 void Col_Max(int col[][Max_AB])
 46 {
 47     deque<node> Q;
 48     for (int j = 1;j <= B;++j)
 49     {
 50         Q.clear();
 51         for (int i = 1;i <= A;++i)
 52         {
 53             while (!Q.empty() && Q.back().Value < Value[i][j])
 54                 Q.pop_back();
 55             Q.push_back(node(i, Value[i][j]));
 56             if (Q.front().Number < i - N + 1)
 57                 Q.pop_front();
 58             col[i][j] = Q.front().Value;
 59         }
 60     }
 61 }
 62 
 63 void Row_Max(int col[][Max_AB], int row[][Max_AB])
 64 {
 65     deque<node> Q;
 66     for (int i = 1;i <= A;++i)
 67     {
 68         Q.clear();
 69         for (int j = 1;j <= B;++j)
 70         {
 71             while (!Q.empty() && Q.back().Value < col[i][j])
 72                 Q.pop_back();
 73             Q.push_back(node(j, col[i][j]));
 74             if (Q.front().Number < j - N + 1)
 75                 Q.pop_front();
 76             row[i][j] = Q.front().Value;
 77         }
 78     }
 79 }
 80 
 81 void work()
 82 {
 83     Col_Max(colmax);
 84     Row_Max(colmax, rowmax);
 85     for (int i = 1;i <= A;++i)
 86         for (int j = 1;j <= B;++j)
 87             Value[i][j] = -Value[i][j];
 88     Col_Max(colmin);
 89     Row_Max(colmin, rowmin);
 90 }
 91 
 92 void Get_Ans()
 93 {
 94     int Ans(0X7F7F7F7F);
 95     for (int i = N;i <= A;++i)
 96         for (int j = N;j <= B;++j)
 97             Ans = min(Ans, rowmax[i][j] + rowmin[i][j]);
 98     printf("%d", Ans);
 99 }
100 
101 int main()
102 {
103     init();
104     work();
105     Get_Ans();
106     return 0;
107 }