2016华为上机题三(最大正方形)

  1 #include <iostream>
  2 #include <stdio.h>
  3 #include <cmath>
  4 #include <string>
  5 #include <vector>
  6 #include <algorithm>
  7 #include <memory.h>
  8 #include <stack>
  9 
 10 using namespace std;
 11 
 12 const double PI = acos(-1.0);
 13 const double eps = 1e-6;
 14 const double INF = 1e9 + 7;
 15 
 16 
 17 
 18 int Min(int a, int b, int c)
 19 {
 20     int m = a;
 21     if (m > b)
 22         m = b;
 23     if (m > c)
 24         m = c;
 25     return m;
 26 }
 27 
 28 
 29 int main()
 30 {
 31     freopen("data.in", "r", stdin);
 32 
 33     int n, m;
 34 
 35     cin >> n >> m;
 36 
 37     if (n == 0 && m == 0)
 38     {
 39         cout << 0 << endl;
 40         return 0;
 41     }
 42     vector<int> row(m, 0);
 43     vector<vector<int> > matrix(n, row);
 44 
 45 
 46     for (int i = 0; i < n; i++)
 47     {
 48         for (int j = 0; j < m; j++)
 49         {
 50             cin >> matrix[i][j];
 51         }
 52     }
 53 
 54     int** dp = new int*[n];
 55     for (int i = 0; i < n; ++i){
 56         dp[i] = new int[m];
 57         memset(dp[i], 0, sizeof(int)*(m));
 58     }
 59 
 60 
 61     for (int j = 0; j < m; ++j)
 62         if (matrix[0][j] == 1)
 63             dp[0][j] = 1;
 64 
 65     for (int i = 0; i < n; ++i)
 66         if (matrix[i][0] == 1)
 67                 dp[i][0] = 1;
 68 
 69     
 70     for (int i = 1; i < n; i++)
 71     {
 72         for (int j = 1; j < m; j++)
 73         {
 74             if (matrix[i][j] == 1)
 75             {
 76                 dp[i][j] = Min(dp[i-1][j],dp[i][j-1], dp[i-1][j-1])+1;
 77             }
 78         }
 79     }
 80     
 81     int maxArea = dp[0][0];
 82     for (int i = 0; i < n; i++)
 83     {
 84         for (int j = 0; j < m; j++)
 85         {
 86             if (maxArea<dp[i][j])
 87             {
 88                 maxArea = dp[i][j];
 89             }
 90                 
 91         }
 92 
 93     }
 94 
 95     cout <<maxArea << endl;
 96 
 97     for (int i = 0; i < m; ++i)
 98         delete[] dp[i];
 99     delete[] dp;
100 
101 
102 
103 
104     system("pause");
105     return 0;
106 }

 1 #include <iostream>
 2 #include <stdio.h>
 3 #include <cmath>
 4 #include <string>
 5 #include <vector>
 6 #include <algorithm>
 7 #include <memory.h>
 8 #include <stack>
 9 
10 using namespace std;
11 
12 const double PI = acos(-1.0);
13 const double eps = 1e-6;
14 const double INF = 1e9 + 7;
15 
16 
17 
18 int largestRectangleArea(int* height, int length) {
19  stack<int> stk;
20  int i = 0;
21  int maxArea = 0;
22  while (i < length){
23   if (stk.empty() || height[stk.top()] <= height[i]){
24    stk.push(i++);
25   }
26   else {
27    int t = stk.top();
28    stk.pop();
29    int area = height[t] * (stk.empty() ? i : i - stk.top() - 1);
30    maxArea = maxArea > area ? maxArea : area;
31   }
32  }
33  return maxArea;
34 }
35 
36 
37 int main()
38 {
39  freopen("data.in", "r", stdin);
40  
41  int n, m;
42 
43  cin >> n >> m;
44  
45  if (n == 0 && m == 0)
46  {
47   cout << 0<< endl;
48   return 0;
49  }
50  vector<int> row(m,0);
51  vector<vector<int> > matrix(n, row);
52  
53 
54  for (int i = 0; i < n; i++)
55  {
56   for (int j = 0; j < m; j++)
57   {
58    cin >> matrix[i][j];
59   }
60  }
61 
62  int** dp = new int*[n];
63  for (int i = 0; i < n; ++i){
64   dp[i] = new int[m + 1];
65   memset(dp[i], 0, sizeof(int)*(m + 1));
66  }
67 
68 
69  for (int j = 0; j < m; ++j)
70   if (matrix[0][j] == 1)
71    dp[0][j] = 1;
72 
73  for (int j = 0; j < m; ++j)
74   for (int i = 1; i < n; ++i)
75    if (matrix[i][j] == 1) 
76     dp[i][j] = dp[i - 1][j] + 1;
77 
78  int maxarea = 0;
79  for (int i = 0; i < n; ++i){
80   int tmp = largestRectangleArea(dp[i], m + 1);
81   if (tmp > maxarea)
82    maxarea = tmp;
83  }
84 
85  cout << maxarea<< endl;
86 
87  for (int i = 0; i < m; ++i)
88   delete[] dp[i];
89  delete[] dp;
90 
91  
92 
93 
94  system("pause");
95  return 0;
96 }