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Commit 39b47ca

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Optimize solution of InfectionDistribution task
1 parent 39a8668 commit 39b47ca

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3 files changed

+34
-176
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3 files changed

+34
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‎README.md‎

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -161,7 +161,7 @@ notes about interview preparation and useful links.
161161
| Удаление элемента заданной величины из массива (leetcode) | [Youtube](https://youtu.be/ECdosiz1ZPM) | [Code](src/main/java/by/andd3dfx/common/RemoveElement.java) |
162162
| ДВЕ задачи про ДВЕри | [Youtube](https://youtu.be/ix81AbCNiBE) | [Code](src/main/java/by/andd3dfx/common/DoorNBox.java) [Code2](src/main/java/by/andd3dfx/common/DoorsNKeys.java) |
163163
| Добавление многопоточности при параллельных запросах в разные системы | [Youtube](https://youtu.be/3IGsZy0uTSk) | [Code](src/main/java/by/andd3dfx/multithreading/AddMultithreading.java) |
164-
| Распространение чумы между городами (2 решения) | [Youtube](https://youtu.be/Ei1uCCD_Iqg) | [Code](src/main/java/by/andd3dfx/common/InfectionDistribution.java) |
164+
| Распространение заражения между городами (2 решения) | [Youtube](https://youtu.be/Ei1uCCD_Iqg) | - |
165165
| Реверсирование порядка цифр в числе (2 решения) | [Youtube](https://youtu.be/w3C4L7GxD7M) | [Code](src/main/java/by/andd3dfx/numeric/ReverseDigitsOrder.java) |
166166
| Поиск среди пар чисел значения, встречающегося однажды: магия XOR (2 решения) (leetcode) | [Youtube](https://youtu.be/dNB8tOvx5Gk) | [Code](src/main/java/by/andd3dfx/numeric/FindNumberWhichAppearsOnce.java) |
167167
| Удаление дубликатов в сортированном связном списке ч.I, II (leetcode) | [Youtube](https://youtu.be/ryE_Q_AtAg8) | [Code](src/main/java/by/andd3dfx/collections/RemoveDuplicatesFromSortedLinkedList.java) [Code2](src/main/java/by/andd3dfx/collections/RemoveDuplicatesFromSortedLinkedList_II.java) |
@@ -265,3 +265,4 @@ notes about interview preparation and useful links.
265265
| 7 классических задач (музыкальный выпуск) | [Youtube](https://youtu.be/KlD0hWZLFbg) | - |
266266
| Решение дифф. уравнений в ЧП на Java численно | [Youtube](https://youtu.be/AmPgu9vksTU) | [Repo](https://github.com/andrei-punko/pde-solvers) |
267267
| 5 сортировок (музыкальный выпуск) | [Youtube](https://youtu.be/tOu0W-hkFCE) | - |
268+
| Распространение заражения между городами 2: матрица смежности | [Youtube](https://youtu.be/d9v9DS1YVtk) | [Code](src/main/java/by/andd3dfx/common/InfectionDistribution.java) |
Lines changed: 19 additions & 100 deletions
Original file line numberDiff line numberDiff line change
@@ -1,11 +1,7 @@
11
package by.andd3dfx.common;
22

3-
import lombok.Data;
4-
53
import java.util.Arrays;
6-
import java.util.HashMap;
74
import java.util.HashSet;
8-
import java.util.Map;
95
import java.util.Set;
106
import java.util.stream.Collectors;
117

@@ -29,118 +25,41 @@
2925
*/
3026
public class InfectionDistribution {
3127

32-
/**
33-
* Initial solution
34-
*/
35-
public static int weeksToInfectAllCities_usingIterationByRoads(int citiesAmount, int[][] roads, int[] infected) {
36-
int weeksCount = 0;
37-
var infectedCitiesSet = Arrays.stream(infected).boxed()
38-
.collect(Collectors.toSet());
39-
var roadsSet = buildRoadsSet(roads);
40-
41-
while (!isAllInfected(citiesAmount, infectedCitiesSet)) {
42-
var infectedOnThisIteration = processOneWeek(roadsSet, infectedCitiesSet);
43-
44-
if (infectedOnThisIteration == 0) {
45-
throw new IllegalArgumentException("Could not infect all cities!");
46-
}
47-
weeksCount++;
48-
}
49-
50-
return weeksCount;
51-
}
52-
53-
private static boolean isAllInfected(int citiesAmount, Set<Integer> infectedCitiesSet) {
54-
return infectedCitiesSet.size() == citiesAmount;
55-
}
56-
57-
private static Set<Road> buildRoadsSet(int[][] roads) {
58-
return Arrays.stream(roads)
59-
.map(Road::new)
60-
.collect(Collectors.toSet());
61-
}
62-
63-
private static int processOneWeek(Set<Road> roads, Set<Integer> infectedCitiesSet) {
64-
var initialCitiesSet = new HashSet<>(infectedCitiesSet);
65-
66-
var it = roads.iterator();
67-
while (it.hasNext()) {
68-
var road = it.next();
69-
70-
if (initialCitiesSet.contains(road.start)) {
71-
infectedCitiesSet.add(road.end);
72-
it.remove();
73-
continue;
74-
}
75-
76-
if (initialCitiesSet.contains(road.end)) {
77-
infectedCitiesSet.add(road.start);
78-
it.remove();
79-
}
80-
}
81-
82-
return infectedCitiesSet.size() - initialCitiesSet.size();
83-
}
84-
85-
@Data
86-
private static class Road {
87-
private int start;
88-
private int end;
89-
90-
public Road(int[] road) {
91-
this.start = road[0];
92-
this.end = road[1];
93-
}
94-
}
95-
96-
/**
97-
* Enhanced solution
98-
*/
99-
public static int weeksToInfectAllCities_usingIterationByInfectedCities(int citiesAmount, int[][] roads, int[] infected) {
100-
var routesMap = new HashMap<Integer, Set<Integer>>();
28+
public static int weeksToInfectAllCities(int citiesAmount, int[][] roads, int[] infected) {
29+
var adjMatrix = new boolean[citiesAmount][citiesAmount]; // adjacency matrix
10130
Arrays.stream(roads).forEach(road -> {
102-
populate(routesMap, road, 0, 1);
103-
populate(routesMap, road, 1, 0);
31+
adjMatrix[road[0]][road[1]] = true;
32+
adjMatrix[road[1]][road[0]] = true;
10433
});
10534

10635
var weeksAmount = 0;
10736
var infectedCities = Arrays.stream(infected).boxed().collect(Collectors.toSet());
108-
var sourceCities = new HashSet<>(infectedCities);
10937

110-
while (!isAllInfected(citiesAmount, infectedCities)) {
111-
if (sourceCities.isEmpty()) {
112-
throw new IllegalArgumentException("Could not infect all cities!");
38+
while (infectedCities.size() < citiesAmount) {
39+
var newCities = determineNewInfectedCities(infectedCities, adjMatrix);
40+
if (newCities.isEmpty()) {
41+
return -1;
11342
}
11443

115-
var newInfectedCities = determineNewInfectedCities(routesMap, infectedCities, sourceCities);
116-
infectedCities.addAll(newInfectedCities);
117-
sourceCities = newInfectedCities;
44+
infectedCities.addAll(newCities);
45+
11846
weeksAmount++;
11947
}
12048

12149
return weeksAmount;
12250
}
12351

124-
private static HashSet<Integer> determineNewInfectedCities(
125-
Map<Integer, Set<Integer>> routesMap, Set<Integer> infectedCities, Set<Integer> sourceCities) {
126-
var newInfectedCities = new HashSet<Integer>();
127-
for (var city : sourceCities) {
128-
if (!routesMap.containsKey(city)) {
129-
continue;
52+
private static Set<Integer> determineNewInfectedCities(Set<Integer> infectedCities, boolean[][] adjMatrix) {
53+
var n = adjMatrix.length;
54+
var newCities = new HashSet<Integer>();
55+
for (var city : infectedCities) {
56+
for (int i = 0; i < n; i++) {
57+
if (adjMatrix[city][i] && !infectedCities.contains(i)) {
58+
newCities.add(i);
59+
}
13060
}
131-
132-
var citiesToInfect = new HashSet<>(routesMap.get(city));
133-
citiesToInfect.removeAll(infectedCities);
134-
135-
newInfectedCities.addAll(citiesToInfect);
13661
}
137-
return newInfectedCities;
138-
}
13962

140-
private static void populate(Map<Integer, Set<Integer>> routesMap, int[] road, int i, int j) {
141-
if (!routesMap.containsKey(road[i])) {
142-
routesMap.put(road[i], new HashSet<>());
143-
}
144-
routesMap.get(road[i]).add(road[j]);
63+
return newCities;
14564
}
14665
}

‎src/test/java/by/andd3dfx/common/InfectionDistributionTest.java‎

Lines changed: 13 additions & 75 deletions
Original file line numberDiff line numberDiff line change
@@ -2,28 +2,26 @@
22

33
import org.junit.Test;
44

5-
import static by.andd3dfx.common.InfectionDistribution.weeksToInfectAllCities_usingIterationByInfectedCities;
6-
import static by.andd3dfx.common.InfectionDistribution.weeksToInfectAllCities_usingIterationByRoads;
5+
import static by.andd3dfx.common.InfectionDistribution.weeksToInfectAllCities;
76
import static org.assertj.core.api.Assertions.assertThat;
8-
import static org.junit.Assert.assertThrows;
97

108
public class InfectionDistributionTest {
119

1210
@Test
13-
public void weeksToInfectAllCitiesPositive_usingIterationByRoads() {
14-
assertThat(weeksToInfectAllCities_usingIterationByRoads(
11+
public void weeksToInfectAllCitiesPositive() {
12+
assertThat(weeksToInfectAllCities(
1513
1,
1614
new int[][]{},
1715
new int[]{0}
1816
)).isEqualTo(0);
1917

20-
assertThat(weeksToInfectAllCities_usingIterationByRoads(
18+
assertThat(weeksToInfectAllCities(
2119
2,
2220
new int[][]{new int[]{0, 1}},
2321
new int[]{0}
2422
)).isEqualTo(1);
2523

26-
assertThat(weeksToInfectAllCities_usingIterationByRoads(
24+
assertThat(weeksToInfectAllCities(
2725
5,
2826
new int[][]{
2927
new int[]{0, 2},
@@ -33,7 +31,7 @@ public void weeksToInfectAllCitiesPositive_usingIterationByRoads() {
3331
new int[]{0, 3}
3432
)).isEqualTo(2);
3533

36-
assertThat(weeksToInfectAllCities_usingIterationByRoads(
34+
assertThat(weeksToInfectAllCities(
3735
7,
3836
new int[][]{
3937
new int[]{0, 2},
@@ -48,80 +46,20 @@ public void weeksToInfectAllCitiesPositive_usingIterationByRoads() {
4846
}
4947

5048
@Test
51-
public void weeksToInfectAllCitiesNegative_usingIterationByRoads() {
52-
assertThrows("Could not infect all cities!", IllegalArgumentException.class,
53-
() -> weeksToInfectAllCities_usingIterationByRoads(
54-
1,
55-
new int[][]{},
56-
new int[]{}
57-
));
58-
59-
assertThrows("Could not infect all cities!", IllegalArgumentException.class,
60-
() -> weeksToInfectAllCities_usingIterationByRoads(
61-
5,
62-
new int[][]{
63-
new int[]{0, 2},
64-
new int[]{1, 4},
65-
},
66-
new int[]{0, 3}
67-
));
68-
}
69-
70-
@Test
71-
public void weeksToInfectAllCitiesPositive_usingIterationByCities() {
72-
assertThat(weeksToInfectAllCities_usingIterationByInfectedCities(
49+
public void weeksToInfectAllCitiesNegative() {
50+
assertThat(weeksToInfectAllCities(
7351
1,
7452
new int[][]{},
75-
new int[]{0}
76-
)).isEqualTo(0);
53+
new int[]{}
54+
)).isEqualTo(-1);
7755

78-
assertThat(weeksToInfectAllCities_usingIterationByInfectedCities(
79-
2,
80-
new int[][]{new int[]{0, 1}},
81-
new int[]{0}
82-
)).isEqualTo(1);
83-
84-
assertThat(weeksToInfectAllCities_usingIterationByInfectedCities(
56+
assertThat(weeksToInfectAllCities(
8557
5,
8658
new int[][]{
8759
new int[]{0, 2},
88-
new int[]{1, 2},
89-
new int[]{3, 4},
60+
new int[]{1, 4},
9061
},
9162
new int[]{0, 3}
92-
)).isEqualTo(2);
93-
94-
assertThat(weeksToInfectAllCities_usingIterationByInfectedCities(
95-
7,
96-
new int[][]{
97-
new int[]{0, 2},
98-
new int[]{1, 2},
99-
new int[]{3, 4},
100-
new int[]{6, 4},
101-
new int[]{6, 5},
102-
new int[]{1, 5},
103-
},
104-
new int[]{0}
105-
)).isEqualTo(6);
106-
}
107-
108-
@Test
109-
public void weeksToInfectAllCitiesNegative_usingIterationByCities() {
110-
assertThrows("Could not infect all cities!", IllegalArgumentException.class,
111-
() -> weeksToInfectAllCities_usingIterationByInfectedCities(
112-
1,
113-
new int[][]{},
114-
new int[]{}
115-
));
116-
117-
assertThrows("Could not infect all cities!", IllegalArgumentException.class,
118-
() -> weeksToInfectAllCities_usingIterationByInfectedCities(
119-
5,
120-
new int[][]{
121-
new int[]{0, 2},
122-
new int[]{1, 4},
123-
},
124-
new int[]{0, 3}
125-
));
63+
)).isEqualTo(-1);
12664
}
12765
}

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