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javadevjavadev
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Improved task 2508
1 parent 777eb7b commit 4220acb

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2 files changed

+107
-60
lines changed
  • src
    • main/java/g2501_2600/s2508_add_edges_to_make_degrees_of_all_nodes_even
    • test/java/g2501_2600/s2508_add_edges_to_make_degrees_of_all_nodes_even

2 files changed

+107
-60
lines changed

‎src/main/java/g2501_2600/s2508_add_edges_to_make_degrees_of_all_nodes_even/Solution.java‎

Lines changed: 38 additions & 60 deletions
Original file line numberDiff line numberDiff line change
@@ -1,85 +1,63 @@
11
package g2501_2600.s2508_add_edges_to_make_degrees_of_all_nodes_even;
22

3-
// #Hard #Hash_Table #Graph #2023_03_20_Time_33_ms_(100.00%)_Space_109.7_MB_(42.70%)
3+
// #Hard #Hash_Table #Graph #2023_04_18_Time_36_ms_(95.00%)_Space_86.3_MB_(93.33%)
44

55
import java.util.ArrayList;
6-
import java.util.HashSet;
76
import java.util.List;
8-
import java.util.Set;
97

108
@SuppressWarnings("unchecked")
119
public class Solution {
1210
public boolean isPossible(int n, List<List<Integer>> edges) {
13-
// first find odd edge nodes
14-
int[] degree = new int[n + 1];
11+
ArrayList<Integer>[] g = new ArrayList[n + 1];
12+
ArrayList<Integer> oddList = new ArrayList<>();
13+
for (int i = 1; i <= n; i++) {
14+
g[i] = new ArrayList<>();
15+
}
1516
for (List<Integer> edge : edges) {
16-
degree[edge.get(0)]++;
17-
degree[edge.get(1)]++;
17+
int x = edge.get(0);
18+
int y = edge.get(1);
19+
g[x].add(y);
20+
g[y].add(x);
1821
}
19-
List<Integer> oddNodes = new ArrayList<>();
2022
for (int i = 1; i <= n; i++) {
21-
if ((degree[i] & 1) == 1) {
22-
oddNodes.add(i);
23-
}
24-
if (oddNodes.size() > 4) {
25-
// cannot be larger than four
26-
return false;
23+
if (g[i].size() % 2 == 1) {
24+
oddList.add(i);
2725
}
2826
}
29-
if ((oddNodes.size() & 1) == 1) {
30-
// can only have even numbers of odd nodes
31-
return false;
32-
} else if (oddNodes.isEmpty()) {
33-
// zero situation
27+
int size = oddList.size();
28+
if (size == 0) {
3429
return true;
3530
}
36-
// find all edges of oddListNode
37-
Set[] adjList = new HashSet[oddNodes.size()];
38-
for (int i = 0; i < oddNodes.size(); i++) {
39-
adjList[i] = new HashSet<>();
31+
if (size == 1 || size == 3 || size > 4) {
32+
return false;
4033
}
41-
for (List<Integer> edge : edges) {
42-
for (int i = 0; i < oddNodes.size(); i++) {
43-
if ((int) edge.get(0) == oddNodes.get(i)) {
44-
adjList[i].add(edge.get(1));
45-
}
46-
if ((int) edge.get(1) == oddNodes.get(i)) {
47-
adjList[i].add(edge.get(0));
48-
}
34+
if (size == 2) {
35+
int x = oddList.get(0);
36+
int y = oddList.get(1);
37+
if (isNotConnected(x, y, g)) {
38+
return true;
4939
}
50-
}
51-
// to see if it is two or four
52-
if (oddNodes.size() == 4) {
53-
// can only connect each other
54-
// have to detect if they have an edge or not
55-
return adjList[0].size() < (n - 1)
56-
&& adjList[1].size() < (n - 1)
57-
&& adjList[2].size() < (n - 1)
58-
&& adjList[3].size() < (n - 1)
59-
&& ((!adjList[0].contains(oddNodes.get(1))
60-
&& !adjList[1].contains(oddNodes.get(0))
61-
&& !adjList[2].contains(oddNodes.get(3))
62-
&& !adjList[3].contains(oddNodes.get(2)))
63-
|| (!adjList[0].contains(oddNodes.get(2))
64-
&& !adjList[2].contains(oddNodes.get(0))
65-
&& !adjList[1].contains(oddNodes.get(3))
66-
&& !adjList[3].contains(oddNodes.get(1)))
67-
|| (!adjList[0].contains(oddNodes.get(3))
68-
&& !adjList[1].contains(oddNodes.get(2))
69-
&& !adjList[2].contains(oddNodes.get(1))));
70-
} else {
71-
// if two dont have an edge, could use it
72-
if (adjList[0].contains(oddNodes.get(1))) {
73-
// need to find a spare node
74-
for (int i = 1; i <= n; i++) {
75-
if (adjList[0].contains(i) || adjList[1].contains(i)) {
76-
continue;
77-
}
40+
for (int i = 1; i <= n; i++) {
41+
if (isNotConnected(i, x, g) && isNotConnected(i, y, g)) {
7842
return true;
7943
}
80-
return false;
8144
}
45+
return false;
46+
}
47+
int a = oddList.get(0);
48+
int b = oddList.get(1);
49+
int c = oddList.get(2);
50+
int d = oddList.get(3);
51+
if (isNotConnected(a, b, g) && isNotConnected(c, d, g)) {
8252
return true;
8353
}
54+
if (isNotConnected(a, c, g) && isNotConnected(b, d, g)) {
55+
return true;
56+
}
57+
return isNotConnected(a, d, g) && isNotConnected(b, c, g);
58+
}
59+
60+
private boolean isNotConnected(int x, int y, ArrayList<Integer>[] g) {
61+
return !g[x].contains(y);
8462
}
8563
}

‎src/test/java/g2501_2600/s2508_add_edges_to_make_degrees_of_all_nodes_even/SolutionTest.java‎

Lines changed: 69 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -34,4 +34,73 @@ void isPossible3() {
3434
.isPossible(4, ArrayUtils.getLists(new int[][] {{1, 2}, {1, 3}, {1, 4}})),
3535
equalTo(false));
3636
}
37+
38+
@Test
39+
void isPossible4() {
40+
assertThat(
41+
new Solution()
42+
.isPossible(
43+
21,
44+
ArrayUtils.getLists(
45+
new int[][] {
46+
{2, 19}, {16, 17}, {8, 14}, {2, 16}, {12, 20}, {12, 14},
47+
{16, 18}, {15, 16}, {10, 21}, {3, 5}, {13, 18},
48+
{17, 20}, {14, 17}, {9, 12}, {5, 15}, {5, 6}, {3, 7},
49+
{2, 21}, {10, 13}, {8, 16}, {7, 18}, {4, 6}, {9, 1},
50+
{13, 21}, {18, 20}, {7, 14}, {4, 19}, {5, 8}, {3, 11},
51+
{11, 1}, {7, 12}, {4, 7}, {3, 16}, {13, 17}, {17, 19},
52+
{9, 13}, {7, 19}, {10, 16}, {4, 13}, {4, 5}, {2, 15},
53+
{12, 19}, {11, 16}, {2, 9}, {11, 17}, {17, 1}, {16, 21},
54+
{4, 10}, {10, 14}, {14, 16}, {4, 1}, {13, 20}, {5, 20},
55+
{4, 14}, {4, 21}, {10, 20}, {2, 14}, {8, 15}, {4, 8},
56+
{6, 19}, {15, 1}, {19, 1}, {8, 19}, {15, 21}, {3, 12},
57+
{11, 18}, {9, 17}, {18, 19}, {7, 21}, {3, 21}, {16, 19},
58+
{11, 15}, {5, 1}, {8, 17}, {3, 15}, {8, 1}, {10, 19},
59+
{3, 8}, {6, 16}, {2, 8}, {5, 18}, {11, 13}, {11, 20},
60+
{14, 21}, {6, 20}, {4, 20}, {12, 13}, {5, 12}, {10, 11},
61+
{9, 15}, {3, 19}, {9, 20}, {14, 18}, {21, 1}, {13, 19},
62+
{8, 21}, {2, 13}, {3, 10}, {9, 18}, {19, 21}, {6, 7},
63+
{3, 18}, {2, 18}, {6, 14}, {3, 17}, {5, 21}, {14, 20},
64+
{8, 9}, {16, 1}, {3, 4}, {13, 1}, {5, 9}, {4, 15},
65+
{17, 21}, {20, 21}, {2, 17}, {13, 14}, {11, 14},
66+
{9, 16}, {10, 18}, {6, 15}, {6, 12}, {3, 13}, {5, 11},
67+
{6, 1}, {12, 17}, {8, 10}, {5, 10}, {8, 18}, {4, 12},
68+
{10, 1}, {6, 13}, {4, 18}, {7, 20}, {7, 16}, {2, 6},
69+
{12, 21}, {4, 17}, {15, 18}, {13, 16}, {15, 20},
70+
{7, 10}, {6, 10}, {2, 20}, {7, 15}, {18, 1}, {12, 1},
71+
{3, 20}, {7, 1}, {14, 15}, {4, 9}, {11, 19}, {7, 9},
72+
{5, 17}, {18, 21}, {6, 21}, {8, 11}, {6, 17}, {3, 14},
73+
{7, 11}, {5, 7}, {7, 13}, {6, 8}, {6, 9}, {10, 12},
74+
{5, 16}, {2, 4}, {17, 18}, {9, 11}, {12, 16}, {3, 6},
75+
{12, 18}, {3, 9}, {11, 12}, {14, 19}, {10, 15}, {5, 13},
76+
{8, 13}, {15, 17}, {2, 10}, {11, 21}, {20, 1}, {6, 18},
77+
{2, 12}, {19, 20}, {6, 11}, {8, 12}, {2, 3}, {12, 15},
78+
{2, 11}, {9, 10}, {7, 17}, {9, 19}, {13, 15}, {7, 8},
79+
{4, 11}, {2, 5}, {5, 19}, {16, 20}, {15, 19}, {9, 14},
80+
{14, 1}, {10, 17}, {9, 21}, {2, 7}, {8, 20}, {5, 14},
81+
{4, 16}
82+
})),
83+
equalTo(true));
84+
}
85+
86+
@Test
87+
void isPossible5() {
88+
assertThat(
89+
new Solution()
90+
.isPossible(
91+
6,
92+
ArrayUtils.getLists(
93+
new int[][] {{1, 6}, {1, 3}, {1, 4}, {4, 5}, {5, 2}})),
94+
equalTo(true));
95+
}
96+
97+
@Test
98+
void isPossible6() {
99+
assertThat(
100+
new Solution()
101+
.isPossible(
102+
4,
103+
ArrayUtils.getLists(new int[][] {{4, 1}, {3, 2}, {2, 4}, {1, 3}})),
104+
equalTo(true));
105+
}
37106
}

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