From 0144b21da618acf0737d3ee35b2aaa41e2064a27 Mon Sep 17 00:00:00 2001
From: Haidong Ji
Date: Wed, 29 Aug 2018 21:06:31 -0500
Subject: Partial Fib sum last digit done for C++

This concludes the second module of Algorithmic Design and Techniques
from edX. I had a lot of fun doing it. It's challenging and I learned a
lot!---
 PlaygroundCpp/Sources/Playground.cpp | 57 ++++++++++++++++--------------------
 1 file changed, 25 insertions(+), 32 deletions(-)

diff --git a/PlaygroundCpp/Sources/Playground.cpp b/PlaygroundCpp/Sources/Playground.cpp
index 4445c37..c737a3c 100644
--- a/PlaygroundCpp/Sources/Playground.cpp
+++ b/PlaygroundCpp/Sources/Playground.cpp
@@ -26,46 +26,39 @@ static int getLastDigit(long n) {
 	else
 		return result - 1;
 }
+static int getLastDigit(long m, long n) {
+	if (m == n)
+		return getFibNModM(n);
+	else {
+		int sumFn = getLastDigit(n);
+		int sumFm;
+		if (m <= 1)
+			sumFm = 0;
+		else
+			sumFm = getLastDigit(m - 1);
+		if (sumFn >= sumFm)
+			return sumFn - sumFm;
+		else
+			return sumFn - sumFm + 10;
+	}
+}
 
-//TEST(FibSumLastDigitTest, Zero) {
-//	ASSERT_EQ(getLastDigit(0), 0);
-//}
-//TEST(FibSumLastDigitTest, One) {
-//	ASSERT_EQ(getLastDigit(1), 1);
-//}
-//TEST(FibSumLastDigitTest, Six) {
-//	ASSERT_EQ(getLastDigit(6), 0);
-//}
-//TEST(FibSumLastDigitTest, Nine) {
-//	ASSERT_EQ(getLastDigit(9), 8);
-//}
-//TEST(FibSumLastDigitTest, OneHundred) {
-//	ASSERT_EQ(getLastDigit(100), 5);
-//}
-
-//TEST(FibLastDigitTest, One) {
-//	ASSERT_EQ(getFibNModM(239, 1000), 161);
-//}
-//
-//TEST(FibLastDigitTest, Three) {
-//	ASSERT_EQ(getFibNModM(2816213588, 30524), 10249);
-//}
-
-//TEST(FibLastDigitTest, Forty) {
-//	ASSERT_EQ(1344, getGCD(1344, 1344));
+//TEST(FibPartialSumLastDigit, Five_Five) {
+//	ASSERT_EQ(getLastDigit(5, 5), 5);
 //}
 //
-//TEST(FibLastDigitTest, ThreeThreeOne) {
-//	ASSERT_EQ(4, getGCD(14159572, 63967072));
+//TEST(FibPartialSumLastDigit, Ten_200) {
+//	ASSERT_EQ(getLastDigit(10, 200), 2);
 //}
 //
-//TEST(FibLastDigitTest, ReverseAB) {
-//	ASSERT_EQ(4, getGCD(14159572, 63967072));
+//TEST(FibPartialSumLastDigit, One_2) {
+//	ASSERT_EQ(getLastDigit(1, 2), 2);
 //}
 
 int main() {
-	long n;
+	long m, n;
+	std::cin >> m;
 	std::cin >> n;
-	int c = getLastDigit(n);
+	int c = getLastDigit(m, n);
 	std::cout << c << '\n';
 }
-- 
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