refactor 1557

fishercoder1534 · fishercoder1534 · commit 895ff9ff8f9f · 2021-11-01T15:43:02.000-07:00
diff --git a/src/main/java/com/fishercoder/solutions/_1557.java b/src/main/java/com/fishercoder/solutions/_1557.java
@@ -1,27 +1,22 @@
 package com.fishercoder.solutions;
 
 import java.util.ArrayList;
-import java.util.HashMap;
-import java.util.HashSet;
 import java.util.List;
-import java.util.Set;
-import java.util.Map;
 
 public class _1557 {
     public static class Solution1 {
         public List<Integer> findSmallestSetOfVertices(int n, List<List<Integer>> edges) {
-            List<Integer> starts = new ArrayList<>();
-            Map<Integer, Integer> indegree = new HashMap<>();
-            for (int i = 0; i < edges.size(); i++) {
-                int end = edges.get(i).get(1);
-                indegree.put(end, indegree.getOrDefault(end, 0) + 1);
+            int[] indegree = new int[n];
+            for (List<Integer> edge : edges) {
+                indegree[edge.get(1)]++;
             }
-            for (int i = 0; i < n; i++) {
-                if (!indegree.containsKey(i)) {
-                    starts.add(i);
+            List<Integer> ans = new ArrayList<>();
+            for (int i = 0; i < indegree.length; i++) {
+                if (indegree[i] == 0) {
+                    ans.add(i);
                 }
             }
-            return starts;
+            return ans;
         }
     }
 }

Original file line number	Diff line number	Diff line change
`@@ -1,27 +1,22 @@`
`1`	`1`	`package com.fishercoder.solutions;`
`2`	`2`
`3`	`3`	`import java.util.ArrayList;`
`4`		`-import java.util.HashMap;`
`5`		`-import java.util.HashSet;`
`6`	`4`	`import java.util.List;`
`7`		`-import java.util.Set;`
`8`		`-import java.util.Map;`
`9`	`5`
`10`	`6`	`public class _1557 {`
`11`	`7`	`public static class Solution1 {`
`12`	`8`	`public List<Integer> findSmallestSetOfVertices(int n, List<List<Integer>> edges) {`
`13`		`- List<Integer> starts = new ArrayList<>();`
`14`		`- Map<Integer, Integer> indegree = new HashMap<>();`
`15`		`- for (int i = 0; i < edges.size(); i++) {`
`16`		`- int end = edges.get(i).get(1);`
`17`		`- indegree.put(end, indegree.getOrDefault(end, 0) + 1);`
	`9`	`+ int[] indegree = new int[n];`
	`10`	`+ for (List<Integer> edge : edges) {`
	`11`	`+ indegree[edge.get(1)]++;`
`18`	`12`	`}`
`19`		`- for (int i = 0; i < n; i++) {`
`20`		`- if (!indegree.containsKey(i)) {`
`21`		`- starts.add(i);`
	`13`	`+ List<Integer> ans = new ArrayList<>();`
	`14`	`+ for (int i = 0; i < indegree.length; i++) {`
	`15`	`+ if (indegree[i] == 0) {`
	`16`	`+ ans.add(i);`
`22`	`17`	`}`
`23`	`18`	`}`
`24`		`- return starts;`
	`19`	`+ return ans;`
`25`	`20`	`}`
`26`	`21`	`}`
`27`	`22`	`}`