最大公共子序列和最大公共子串

最大公共子序列

int MatchTopic::LongestCommonSequence(const std::string &topic, const std::string &test)
{
	int lengthOfTopic = topic.size();
	int lengthOfTest = test.size();

	std::vector<std::vector<int>> c(lengthOfTopic + 1, std::vector<int>(lengthOfTest + 1, 0));
	for (int i = 0; i <= lengthOfTopic; i++) {
		for (int j = 0; j <= lengthOfTest; j++) {
			if (i == 0 || j == 0) {
				c[i][j] = 0;
			}
			else if (topic[i - 1] == test[j - 1]) {
				c[i][j] = c[i - 1][j - 1] + 1;
			}
			else if (c[i - 1][j] >= c[i][j - 1]) {
				c[i][j] = c[i - 1][j];
			}
			else {
				c[i][j] = c[i][j - 1];
			}
		}
	}
	return c[lengthOfTopic][lengthOfTest];
}

最大公共子串

int MatchTopic::LongestCommonSubstring(const std::string &topic, const std::string &test)
{
	int lengthOfTopic = topic.size();
	int lengthOfTest = test.size();
	int result = 0;     //记录最长公共子串长度

	std::vector<std::vector<int>> c(lengthOfTopic + 1, std::vector<int>(lengthOfTest + 1, 0));
	for (int i = 0; i <= lengthOfTopic; i++) {
		for (int j = 0; j <= lengthOfTest; j++) {
			if (i == 0 || j == 0) {
				c[i][j] = 0;
			}
			else if (topic[i - 1] == test[j - 1]) {
				c[i][j] = c[i - 1][j - 1] + 1;
				if (c[i][j] > result) {
					result = c[i][j];

				}
			}
			else {
				c[i][j] = 0;
			}
		}
	}
	return result;
}