diff --git a/src/main/java/com/odde/tdd/BudgetCalculation.java b/src/main/java/com/odde/tdd/BudgetCalculation.java
new file mode 100644
index 0000000..83186a9
--- /dev/null
+++ b/src/main/java/com/odde/tdd/BudgetCalculation.java
@@ -0,0 +1,65 @@
+package com.odde.tdd;
+
+import java.time.LocalDate;
+import java.time.YearMonth;
+import java.time.temporal.ChronoUnit;
+import java.util.List;
+import java.util.Map;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
+public class BudgetCalculation {
+
+    private final BudgetRepo budgetRepo;
+
+    public BudgetCalculation(BudgetRepo budgetRepo) {
+        this.budgetRepo = budgetRepo;
+    }
+
+    private long calculateOneMonth(Budget budget, int startDay, int endDay) {
+        int totalDays = endDay - startDay + 1;
+        int monthDays = budget.getMonth().lengthOfMonth();
+        if (totalDays == monthDays) {
+            return budget.getAmount();
+        }
+        return totalDays * budget.getAmount() / monthDays;
+    }
+
+    public long calculate(LocalDate startTime, LocalDate endTime) {
+        if(startTime.isAfter(endTime)) {
+            throw new IllegalArgumentException("startTime should be before than endTime.");
+        }
+        long totalBudget = 0;
+        YearMonth startMonth = YearMonth.of(startTime.getYear(), startTime.getMonth());
+        YearMonth endMonth = YearMonth.of(endTime.getYear(), endTime.getMonth());
+        int startDay = startTime.getDayOfMonth();
+        int endDay = endTime.getDayOfMonth();
+        List<Budget> budgetList = budgetRepo.findAll();
+        Map<YearMonth, Budget> budgetMap = budgetList.stream().collect(Collectors.toMap(Budget::getMonth, Function.identity()));
+        for (int i = 0; !startMonth.isAfter(endMonth); ++i) {
+            if (i > 0) {
+                startTime = startTime.plus(1, ChronoUnit.MONTHS);
+                startMonth = YearMonth.of(startTime.getYear(), startTime.getMonth());
+            }
+            Budget budget = budgetMap.get(startMonth);
+            if(budget == null) {
+                startDay = 1;
+                System.out.println("WARNING: No budget for "+ startMonth + " so that the month's budget is 0");
+                continue;
+            }
+            if(i == 0 || startMonth.equals(endMonth)) {
+                // first month or end month
+                if (startMonth.isBefore(endMonth)) {
+                    totalBudget += calculateOneMonth(budget, startDay, budget.getMonth().lengthOfMonth());
+                    startDay = 1;
+                } else if (startMonth.equals(endMonth)) {
+                    totalBudget += calculateOneMonth(budget, startDay, endDay);
+                    break;
+                }
+            } else {
+                totalBudget += budget.getAmount();
+            }
+        }
+        return totalBudget;
+    }
+}
diff --git a/src/main/java/com/odde/tdd/FizzBuzz.java b/src/main/java/com/odde/tdd/FizzBuzz.java
new file mode 100644
index 0000000..cee982d
--- /dev/null
+++ b/src/main/java/com/odde/tdd/FizzBuzz.java
@@ -0,0 +1,21 @@
+package com.odde.tdd;
+
+public class FizzBuzz {
+    public static String fizzBuzz(int n) {
+//        if(n <= 0) {
+//            return "";
+//        }
+        String nStr = String.valueOf(n);
+        StringBuilder sb = new StringBuilder();
+        if((n % 3 == 0) || nStr.contains("3")) {
+            sb.append("Fizz");
+        }
+        if(n % 5 == 0 || nStr.contains("5")) {
+            sb.append("Buzz");
+        }
+        if(sb.length() == 0) {
+            sb.append(n);
+        }
+        return sb.toString();
+    }
+}
diff --git a/src/main/java/com/odde/tdd/PrimaryFactorDecompose.java b/src/main/java/com/odde/tdd/PrimaryFactorDecompose.java
new file mode 100644
index 0000000..0c94ce6
--- /dev/null
+++ b/src/main/java/com/odde/tdd/PrimaryFactorDecompose.java
@@ -0,0 +1,33 @@
+package com.odde.tdd;
+
+import java.util.ArrayList;
+import java.util.List;
+
+public class PrimaryFactorDecompose {
+
+    public static List<Long> decompose_fast(long n) {
+        List<Long> factors = new ArrayList<>();
+        long m = (long)(Math.sqrt(n));
+        for (long i = 2; i <= m && i <= n; ++i) {
+            while(n % i == 0) {
+                factors.add(i);
+                n = n / i;
+            }
+        }
+        if(n > 1) {
+            factors.add(n);
+        }
+        return factors;
+    }
+
+    public static List<Long> decompose(long n) {
+        List<Long> factors = new ArrayList<>();
+        for(long i=2; n>1; ++i) {
+            for(; n % i == 0; n = n / i) {
+                factors.add(i);
+            }
+        }
+        return factors;
+    }
+
+}
diff --git a/src/test/java/com/odde/tdd/BudgetCalculationTest.java b/src/test/java/com/odde/tdd/BudgetCalculationTest.java
new file mode 100644
index 0000000..2e07680
--- /dev/null
+++ b/src/test/java/com/odde/tdd/BudgetCalculationTest.java
@@ -0,0 +1,88 @@
+package com.odde.tdd;
+
+import org.junit.Test;
+
+import java.time.LocalDate;
+import java.time.YearMonth;
+import java.util.Arrays;
+
+import static org.junit.Assert.assertEquals;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+public class BudgetCalculationTest {
+    private BudgetRepo repo = mock(BudgetRepo.class);
+    private BudgetCalculation budgetCalculation = new BudgetCalculation(repo);;
+
+    @Test
+    public void calculate_one_day_normal_month() {
+        LocalDate startTime = LocalDate.parse("2018-11-02");
+        when(repo.findAll()).thenReturn(Arrays.asList(new Budget(YearMonth.of(2018, 11), 300)));
+        assertEquals(10, budgetCalculation.calculate(startTime, startTime));
+    }
+
+    @Test
+    public void calculate_one_day_leap_month() {
+        LocalDate startTime = LocalDate.parse("2018-10-02");
+        when(repo.findAll()).thenReturn(Arrays.asList(new Budget(YearMonth.of(2018, 10), 310)));
+        assertEquals(10, budgetCalculation.calculate(startTime, startTime));
+    }
+
+    @Test
+    public void calculate_one_month() {
+        LocalDate startTime = LocalDate.parse("2018-10-01");
+        LocalDate endTime = LocalDate.parse("2018-10-31");
+        when(repo.findAll()).thenReturn(Arrays.asList(new Budget(YearMonth.of(2018, 10), 310)));
+        assertEquals(310, budgetCalculation.calculate(startTime, endTime));
+    }
+
+    @Test
+    public void calculate_two_days_normal_month() {
+        LocalDate startTime = LocalDate.parse("2018-11-02");
+        LocalDate endTime = LocalDate.parse("2018-11-03");
+        when(repo.findAll()).thenReturn(Arrays.asList(new Budget(YearMonth.of(2018, 11), 300)));
+        assertEquals(20, budgetCalculation.calculate(startTime, endTime));
+    }
+
+    @Test
+    public void calculate_two_months() {
+        LocalDate startTime = LocalDate.parse("2018-11-29");
+        LocalDate endTime = LocalDate.parse("2018-12-03");
+        when(repo.findAll()).thenReturn(Arrays.asList(
+                new Budget(YearMonth.of(2018, 11), 300)
+                , new Budget(YearMonth.of(2018, 12), 310)
+                ));
+        assertEquals(50, budgetCalculation.calculate(startTime, endTime));
+    }
+
+    @Test
+    public void calculate_two_years() {
+        LocalDate startTime = LocalDate.parse("2018-11-29");
+        LocalDate endTime = LocalDate.parse("2019-01-03");
+        when(repo.findAll()).thenReturn(Arrays.asList(
+                new Budget(YearMonth.of(2018, 11), 300)
+                , new Budget(YearMonth.of(2018, 12), 310)
+                , new Budget(YearMonth.of(2019, 1), 310)
+        ));
+        assertEquals(360, budgetCalculation.calculate(startTime, endTime));
+    }
+
+    @Test
+    public void calculate_two_years_missing_one_month_and_disorder() {
+        LocalDate startTime = LocalDate.parse("2018-11-29");
+        LocalDate endTime = LocalDate.parse("2019-01-03");
+        when(repo.findAll()).thenReturn(Arrays.asList(
+                new Budget(YearMonth.of(2019, 1), 310)
+                , new Budget(YearMonth.of(2018, 12), 310)
+        ));
+        assertEquals(340, budgetCalculation.calculate(startTime, endTime));
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void calculate_argument_error() {
+        LocalDate startTime = LocalDate.parse("2018-11-02");
+        LocalDate endtime = LocalDate.parse("2018-10-01");
+        budgetCalculation.calculate(startTime, endtime);
+    }
+
+}
\ No newline at end of file
diff --git a/src/test/java/com/odde/tdd/FizzBuzzTest.java b/src/test/java/com/odde/tdd/FizzBuzzTest.java
new file mode 100644
index 0000000..44a3395
--- /dev/null
+++ b/src/test/java/com/odde/tdd/FizzBuzzTest.java
@@ -0,0 +1,41 @@
+package com.odde.tdd;
+
+import junit.framework.TestCase;
+import org.junit.Assert;
+import org.junit.Test;
+
+public class FizzBuzzTest extends TestCase {
+    @Test
+    public void testFizzBuzz3() {
+        Assert.assertEquals("Fizz", FizzBuzz.fizzBuzz(-3));
+        Assert.assertEquals("Fizz", FizzBuzz.fizzBuzz(3));
+        Assert.assertEquals("Fizz", FizzBuzz.fizzBuzz(9));
+        Assert.assertEquals("Fizz", FizzBuzz.fizzBuzz(13));
+        Assert.assertEquals("Fizz", FizzBuzz.fizzBuzz(33));
+    }
+
+    @Test
+    public void testFizzBuzz5() {
+        Assert.assertEquals("Buzz", FizzBuzz.fizzBuzz(5));
+        Assert.assertEquals("Buzz", FizzBuzz.fizzBuzz(20));
+        Assert.assertEquals("Buzz", FizzBuzz.fizzBuzz(151));
+    }
+
+    @Test
+    public void testFizzBuzz3And5() {
+        Assert.assertEquals("FizzBuzz", FizzBuzz.fizzBuzz(0));
+        Assert.assertEquals("FizzBuzz", FizzBuzz.fizzBuzz(15));
+        Assert.assertEquals("FizzBuzz", FizzBuzz.fizzBuzz(60));
+        Assert.assertEquals("FizzBuzz", FizzBuzz.fizzBuzz(35));
+        Assert.assertEquals("FizzBuzz", FizzBuzz.fizzBuzz(45));
+        Assert.assertEquals("FizzBuzz", FizzBuzz.fizzBuzz(51));
+    }
+
+    @Test
+    public void testFizzBuzzNumber() {
+        Assert.assertEquals("2", FizzBuzz.fizzBuzz(2));
+        Assert.assertEquals("8", FizzBuzz.fizzBuzz(8));
+        Assert.assertEquals("-8", FizzBuzz.fizzBuzz(-8));
+    }
+
+}
\ No newline at end of file
diff --git a/src/test/java/com/odde/tdd/PrimaryFactorDecomposeTest.java b/src/test/java/com/odde/tdd/PrimaryFactorDecomposeTest.java
new file mode 100644
index 0000000..63341ce
--- /dev/null
+++ b/src/test/java/com/odde/tdd/PrimaryFactorDecomposeTest.java
@@ -0,0 +1,59 @@
+package com.odde.tdd;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
+public class PrimaryFactorDecomposeTest {
+
+    @Test
+    public void test_1() {
+        Assert.assertEquals(Collections.emptyList(), PrimaryFactorDecompose.decompose_fast(1L));
+    }
+
+    @Test
+    public void test_2() {
+        Assert.assertEquals(Collections.singletonList(2L), PrimaryFactorDecompose.decompose_fast(2L));
+    }
+
+    @Test
+    public void test_3() {
+        Assert.assertEquals(Collections.singletonList(3L), PrimaryFactorDecompose.decompose_fast(3L));
+    }
+
+    @Test
+    public void test_4() {
+        Assert.assertEquals(Arrays.asList(2L, 2L), PrimaryFactorDecompose.decompose_fast(4L));
+    }
+
+    @Test
+    public void test_6() {
+        Assert.assertEquals(Arrays.asList(2L, 3L), PrimaryFactorDecompose.decompose_fast(6L));
+    }
+
+    @Test
+    public void test_26() {
+        Assert.assertEquals(Arrays.asList(2L, 13L), PrimaryFactorDecompose.decompose_fast(26L));
+    }
+
+    @Test
+    public void test_two_functions() {
+        for(long i=1; i<10000; ++i) {
+            List<Long> listA = PrimaryFactorDecompose.decompose(i);
+            List<Long> listB = PrimaryFactorDecompose.decompose_fast(i);
+            Assert.assertEquals(listA, listB);
+        }
+    }
+
+    @Test
+    public void test_decompose_big_number() {
+        long startTime = System.nanoTime();
+        List<Long> list = PrimaryFactorDecompose.decompose_fast(1232423232232321123L);
+        System.out.println("elapsedTime: " + (System.nanoTime() - startTime));
+        System.out.println("list: " + list);
+    }
+
+}
\ No newline at end of file