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Commitf1c3e93

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05.02 (1) DP
1 parentcb028d7 commitf1c3e93

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/**
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* Time : O() ; Space: O()
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* @tag : LintCode Copyright; Dynamic Programming
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* @by : Steven Cooks
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* @date: Sep 8, 2015
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***************************************************************************
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* Description:
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* Given two strings, find the longest common subsequence (LCS).
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* Your code should return the length of LCS.
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*
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* Example
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* For "ABCD" and "EDCA", the LCS is "A" (or "D", "C"), return 1.
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* For "ABCD" and "EACB", the LCS is "AC", return 2.
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*
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***************************************************************************
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* {@link http://www.lintcode.com/en/problem/longest-common-subsequence }
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*/
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package_02_LongestCommonSubsequence;
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/** see test {@link _02_LongestCommonSubsequence.SolutionTest } */
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publicclassSolution {
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publicintlongestCommonSubsequence(StringA,StringB) {
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int[][]dp =newint[A.length() +1][B.length() +1];
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for (inti =A.length();i >=0;i--) {
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for (intj =B.length();j >=0;j--) {
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intlen =0;
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if (i <A.length() &&j <B.length()) {
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if (A.charAt(i) ==B.charAt(j)) {
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len =1 +dp[i +1][j +1];
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}else {
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len =Math.max(dp[i +1][j],dp[i][j +1]);
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}
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}
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dp[i][j] =len;
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}
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}
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returndp[0][0];
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}
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// verbose bottom-up dynamic programming version
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publicintlongestCommonSubsequence2(StringA,StringB) {
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int[][]dp =newint[A.length() +1][B.length() +1];
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for (inti =A.length();i >=0;i--) {
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for (intj =B.length();j >=0;j--) {
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intlen =0;
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if (i ==A.length() &&j ==B.length()) {
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len =0;
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}elseif (i ==A.length()) {
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len =0;
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}elseif (j ==B.length()) {
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len =0;
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}else {
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if (A.charAt(i) ==B.charAt(j)) {
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len =1 +dp[i +1][j +1];
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}else {
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len =Math.max(dp[i +1][j],dp[i][j +1]);
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}
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}
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dp[i][j] =len;
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}
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}
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returndp[0][0];
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}
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// pure backtracking version
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publicintlongestCommonSubsequence3(StringA,StringB) {
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returnLCS(A,0,B,0);
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}
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privateintLCS(StringA,inti,StringB,intj) {
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if (i ==A.length() &&j ==B.length()) {
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return0;
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}elseif (i ==A.length()) {
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return0;
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}elseif (j ==B.length()) {
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return0;
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}else {
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if (A.charAt(i) ==B.charAt(j)) {
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return1 +LCS(A,i +1,B,j +1);
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}else {
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returnMath.max(LCS(A,i +1,B,j),LCS(A,i,B,j +1));
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}
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}
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}
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}
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package_02_LongestCommonSubsequence;
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importstaticorg.junit.Assert.*;
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importorg.junit.After;
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importorg.junit.Before;
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importorg.junit.Rule;
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importorg.junit.Test;
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importorg.junit.rules.Timeout;
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publicclassSolutionTest {
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/** Test method for {@link _02_LongestCommonSubsequence.Solution } */
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Solutionsolution;
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@Rule
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publicTimeoutglobalTimeout =newTimeout(200);
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@Before
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publicvoidsetUp()throwsException {
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solution =newSolution();
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}
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@After
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publicvoidtearDown()throwsException {
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solution =null;
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}
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@Test
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publicvoidTest1() {
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StringA ="ABCD";
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StringB ="EDCA";
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intactual =solution.longestCommonSubsequence(A,B);
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intexpected =1;
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assertEquals(expected,actual);
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}
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@Test
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publicvoidTest2() {
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StringA ="ABCD";
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StringB ="EACB";
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intactual =solution.longestCommonSubsequence(A,B);
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intexpected =2;
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assertEquals(expected,actual);
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}
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@Test
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publicvoidTest3() {
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StringA ="XYZ";
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StringB ="EACB";
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intactual =solution.longestCommonSubsequence(A,B);
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intexpected =0;
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assertEquals(expected,actual);
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}
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}

‎README.md

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -14,4 +14,5 @@ Selected problems that are included in LintCode but are not included in Leetcode
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| 03.01|[Insert Node in Binary Search Tree](https://github.com/interviewcoder/lintcode/blob/master/03_binarytree%26divideconquer/_01_InsertNodeInABinarySearchTree/Solution.java)| BST`LintCode Copyright`||
1515
| 03.02|[Search Range In Binary Search Tree](https://github.com/interviewcoder/lintcode/blob/master/03_binarytree%26divideconquer/_02_SearchRangeInBinarySearchTree/Solution.java)| Binary Search Tree| in-order + pruning|
1616
| 04.01|[Longest Increasing Subsequence](https://github.com/interviewcoder/lintcode/blob/master/04_dynamicprogrammingI/_01_LongestIncreasingSubsequence/Solution.java)| Dynamic Programming||
17-
| 05.01|[Longest Common Substring](https://github.com/interviewcoder/lintcode/blob/master/05_dynamicprogrammingII/_01_LongestCommonSubstring/Solution.java)| Dynamic Programming||
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| 05.01|[Longest Common Substring](https://github.com/interviewcoder/lintcode/blob/master/05_dynamicprogrammingII/_01_LongestCommonSubstring/Solution.java)| Dynamic Programming||
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| 05.02|[Longest Common Subsequence](https://github.com/interviewcoder/lintcode/blob/master/05_dynamicprogrammingII/_02_LongestCommonSubsequence/Solution.java)| Dynamic Programming||

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