From 1559f265e9f1fcbedd1510949d02f7e661e652a7 Mon Sep 17 00:00:00 2001
From: Haidong Ji
Date: Tue, 25 Dec 2018 15:26:31 -0600
Subject: Longest subsequences (2 seqs) done!

Working with vector in C++ is much easier than arrays!. Plus in Java all
ints are initialized as 0, but not in C++, so I had to add logic to do
that properly.---
 PlaygroundCpp/Sources/Playground.cpp | 79 ++++++++++++++++++++----------------
 1 file changed, 43 insertions(+), 36 deletions(-)

(limited to 'PlaygroundCpp/Sources')

diff --git a/PlaygroundCpp/Sources/Playground.cpp b/PlaygroundCpp/Sources/Playground.cpp
index 373e327..8c8b854 100644
--- a/PlaygroundCpp/Sources/Playground.cpp
+++ b/PlaygroundCpp/Sources/Playground.cpp
@@ -1,58 +1,65 @@
 #include <iostream>
-#include <string>
 #include <algorithm>
+#include <vector>
 //#include <gtest/gtest.h>
 
-using std::string;
+using std::vector;
 
-int editDistance(const string &A, const string &B) {
-	int m = B.length();
-	int n = A.length();
+int lcs2(vector<int> &a, vector<int> &b) {
+	int m = b.size();
+	int n = a.size();
 	int D[n + 1][m + 1];
-
-	for (int i = 0; i < n + 1; i++) {
-		D[i][0] = i;
-	}
 	for (int j = 0; j < m + 1; j++) {
-		D[0][j] = j;
-	}
-
-	for (int j = 1; j < m + 1; j++) {
-		for (int i = 1; i < n + 1; i++) {
-			int insertion = D[i][j - 1] + 1;
-			int deletion = D[i - 1][j] + 1;
-			int match = D[i - 1][j - 1];
-			int mismatch = D[i - 1][j - 1] + 1;
-			if (A.at(i - 1) == B.at(j - 1)) {
-				D[i][j] = std::min(insertion, std::min(deletion, match));
+		for (int i = 0; i < n + 1; i++) {
+	// Initialize row/column 0 to 0 is necessary!
+			if (i == 0 || j == 0) {
+				D[i][j] = 0;
+				continue;
+			}
+			if (a.at(i - 1) == b.at(j - 1)) {
+				D[i][j] = D[i - 1][j - 1] + 1;
 			} else {
-				D[i][j] = std::min(insertion, std::min(deletion, mismatch));
+				D[i][j] = std::max(D[i - 1][j], D[i][j - 1]);
 			}
 		}
 	}
-
 	return D[n][m];
 }
 
-//TEST(EditDistance, d2) {
-//	ASSERT_EQ(0, editDistance("ab", "ab"));
-//}
-//TEST(EditDistance, d1) {
-//	ASSERT_EQ(1, editDistance("a", "x"));
+//TEST(LCS2, t1) {
+//	vector<int> a = { 2, 7, 5 };
+//	vector<int> b = { 2, 5 };
+//	ASSERT_EQ(2, lcs2(a, b));
 //}
 //
-//TEST(EditDistance, d3) {
-//	ASSERT_EQ(3, editDistance("short", "ports"));
+//TEST(LCS2, t2) {
+//	vector<int> a = { 1, 9, 2, 5, 5, 5, 8, 3, 5, 11, 0, 2, 4, 1, 7, 4, 5, 9, 2,
+//			4, 0, 3, 1, 5, 8, 3, 5, 9, 7, 8, 4, 5, 6, 7 };
+//	vector<int> b = { 6, 3, 8, 3, 1, 8, 3, 5, 0, 9, 6, 8, 3, 5, 7, 9, 1, 4, 7,
+//			9, 3, 5, 9, 0, 1, 4, 2, 7, 5, 8, 9, 3, 5, 6, 1, 6, 3, 1, 6, 7, 3 };
+//	ASSERT_EQ(17, lcs2(a, b));
 //}
 //
-//TEST(EditDistance, d4) {
-//	ASSERT_EQ(5, editDistance("editing", "distance"));
+//TEST(LCS2, t3) {
+//	vector<int> a = { 1, 2, 3 };
+//	vector<int> b = { 3, 2, 1 };
+//	ASSERT_EQ(1, lcs2(a, b));
 //}
 
 int main() {
-	string str1;
-	string str2;
-	std::cin >> str1 >> str2;
-	std::cout << editDistance(str1, str2) << std::endl;
-	return 0;
+  size_t n;
+  std::cin >> n;
+  vector<int> a(n);
+  for (size_t i = 0; i < n; i++) {
+    std::cin >> a[i];
+  }
+
+  size_t m;
+  std::cin >> m;
+  vector<int> b(m);
+  for (size_t i = 0; i < m; i++) {
+    std::cin >> b[i];
+  }
+
+  std::cout << lcs2(a, b) << std::endl;
 }
-- 
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