算法导论 ch15 动态规划 最长公共子串

1. 注意区分最长公共子串和最长公共序列

#include <iostream> #include <string> #include <algorithm> using namespace std; string longestCommonSubstring(const string& s1, const string& s2) { if(s1.empty() || s2.empty()) { return 0; } int m = s1.size(); int n = s2.size(); int* table = new int[m * n]; for(int i = 0; i < m; i++) { for(int j = 0; j < n; j++) { if (s1[i] == s2[j]) { if (i == 0 || j == 0) { table[i * n + j] = 1; } else { table[i * n + j] = table[(i-1)*n + j-1] + 1; } } } } for(int i = 0; i < m; i++) { for(int j = 0; j < n; j++) { cout << table[i * n + j] << " "; } cout << endl; } int len = *max_element(table, table + m * n); int dis = max_element(table, table + m * n) - table; int endInS1 = dis / n; string res = s1.substr(endInS1 + 1 - len, len); delete[] table; return res; } int main() { string s1 = "ABCABD"; string s2 = "BABA"; cout << longestCommonSubstring(s1, s2) << endl; }

2. 运行结果

/home/a/j/nomad2:./a.out 0 1 0 1 1 0 2 0 0 0 0 0 0 1 0 1 1 0 2 0 0 0 0 0 AB

reference: http://en.wikibooks.org/wiki/Algorithm_Implementation/Strings/Longest_common_substring