腾讯2016春招之算法编程解析

 1 #define M 100
 2 int dpLCS[M][M]; //设置成全局变量，自动初始化为0
 3 
 4 //动态规划法:最长回文子串，有删除，其实就是求最长公共子序列
 5 int LongestCommonSequence(string str)
 6 {
 7     size_t n = str.size();
 8     if (n == 0 || n == 1)
 9         return 1;
10     
11     string s = str;
12     reverse(s.begin(), s.end());
13 
14     for (size_t i = 1; i <= n; ++ i) {
15         for (size_t j = 1; j <= n; ++ j) {
16             if (str[i-1] == s[j-1]) 
17                 dpLCS[i][j] = dpLCS[i-1][j-1] + 1;
18             else 
19                 dpLCS[i][j] = max(dpLCS[i-1][j], dpLCS[i][j-1]); 
20         }
21     }
22     return dpLCS[n][n];
23 }

 1 void HelixMatrix(int n)
 2 {
 3     int **a = new int *[n];
 4     for (int i = 0; i < n; i ++)
 5         a[i] = new int[n];
 6 
 7     int m = 0;
 8     for (int k = 0; k < n/2; ++ k) { //n/2矩阵个数
 9         for (int i = 0; i <= n-1-k; ++ i)
10             a[k][i] = m++; //第一区块
11         for (int i = k + 1; i < n-1-k; ++ i)
12             a[i][n-1-k] = m++; //第二区块
13         for (int i = n-1-k; i > k; -- i)
14             a[n-1-k][i] = m++; //第三区块
15         for (int i = n-1-k; i > k; -- i)
16             a[i][k] = m ++; //第四区块
17         if (n%2 == 1)
18             a[n/2][n/2] = m; //n=odd，填充中间一个数
19     }
20     for (int i = 0; i < n; i ++) {
21         for (int j = 0; j < n; j ++)
22             cout << a[i][j] << " ";
23         cout << endl;
24     }
25     //释放a
26     for(int i = 0; i < n; i ++) {
27         delete [] a[i];
28     }
29     delete []a;
30 }