[pull] master from yuanguangxin:master #6

Original file line number	Diff line number	Diff line change
Expand Up		@@ -2,7 +2,7 @@

		/**
		* 动态规划 dp[i + 1][j + 1] = Math.max(dp[i+1][j], dp[i][j+1]) o(m*n)
	*
	* <p>
		* 若题目为最长公共子串,则在c1,c2不相等时不做处理(赋值0),在遍历过程中记录最大值即可
		*/
		public class Solution {
Expand All		@@ -25,4 +25,37 @@ public int longestCommonSubsequence(String text1, String text2) {
		}
		return dp[m][n];
		}

	/**
	* 最长公共字串
	*
	* @param str1
	* @param str2
	* @return
	*/
	public static String longestCommonSubstring(String str1, String str2) {
	int m = str1.length();
	int n = str2.length();
	int[][] dp = new int[m + 1][n + 1];
	int maxLength = 0;
	int endIndex = -1;

	for (int i = 1; i <= m; i++) {
	for (int j = 1; j <= n; j++) {
	if (str1.charAt(i - 1) == str2.charAt(j - 1)) {
	dp[i][j] = dp[i - 1][j - 1] + 1;
	if (dp[i][j] > maxLength) {
	maxLength = dp[i][j];
	endIndex = i - 1;
	}
	} else {
	dp[i][j] = 0;
	}
	}
	}
	if (maxLength == 0) {
	return "";
	}
	return str1.substring(endIndex - maxLength + 1, endIndex + 1);
	}
		}

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