SW

s50600822 · Sep 14, 2023 · 013eb97 · 013eb97
1 parent 582264a
commit 013eb97
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Showing 3 changed files with 67 additions and 6 deletions.
diff --git a/interview_prep/algorithm/java17/src/main/java/hoa/can/code/ez/SubArrGivenSum.java b/interview_prep/algorithm/java17/src/main/java/hoa/can/code/ez/SubArrGivenSum.java
@@ -4,8 +4,23 @@
 
 //https://practice.geeksforgeeks.org/problems/subarray-with-given-sum-1587115621/1
 public class SubArrGivenSum {
-    // why int n is here, the industry is trash.
+    public static final int BRUTE_FORCE = 1;
+    public static final int SLIDING_WINDOWS = 1;
+
     public static ArrayList<Integer> subarraySum(int[] arr, int n, int s) {
+        return subarraySum(BRUTE_FORCE, arr, n, s);
+    }
+
+
+    public static ArrayList<Integer> subarraySum(int algo, int[] arr, int n, int s) {
+        if(algo==BRUTE_FORCE){
+            return subarraySum1(arr, n, s);
+        }
+        return subarraySum2(arr, n, s);
+    }
+
+    // why int n is here, the industry is trash.
+    private static ArrayList<Integer> subarraySum1(int[] arr, int n, int s) {
         ArrayList<Integer> result = new ArrayList<>(2);
         for(int start = 0; start < arr.length; start++){
             int remainder = s-arr[start];
@@ -29,4 +44,37 @@ public static ArrayList<Integer> subarraySum(int[] arr, int n, int s) {
         result.add(-1);
         return result;
     }
+
+  private static ArrayList<Integer> subarraySum2(int[] arr, int n, int s) {
+        // sliding window, faster.
+        int start = 0;
+        int end = 0;
+
+        int arrSum = 0;
+        ArrayList<Integer> res = new ArrayList<>();
+
+        while(end < arr.length){
+            arrSum += arr[end];// (1)
+            if(arrSum == s){
+                res.add(start+1);
+                res.add(end+1);
+                return res;
+            }
+            if(arrSum < s){
+                end = end + 1;
+            } else {
+                if(start<end){
+                    arrSum = arrSum - arr[start];
+                    arrSum = arrSum - arr[end]; // compensate (1) cause I dont want to rewrite
+                    start = start + 1;
+                }else{
+                    start = end +1;
+                    end = end +1;
+                    arrSum = 0;
+                }
+            }
+        }
+        res.add(-1);
+        return res;
+    }
 }
diff --git a/interview_prep/algorithm/java17/src/test/java/hoa/can/code/ShortestUnsortedSubArrayTest.java b/interview_prep/algorithm/java17/src/test/java/hoa/can/code/ShortestUnsortedSubArrayTest.java
@@ -2,7 +2,6 @@
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import hoa.can.code.ez.ShortestUnsortedSubArray;
 
-import hoa.can.code.ez.ShortestUnsortedSubArray.*;
 import org.junit.jupiter.api.Test;
 
 public class ShortestUnsortedSubArrayTest {
@@ -17,10 +16,10 @@ public void testSol(ShortestUnsortedSubArray.Sol solution){
         assertEquals(
                 0,
                 t.findShortestUnorderedSubarray(new int[]{1, 2, 3, 4, 5})
-        );                
+        );
         assertEquals(
                 3,
                 t.findShortestUnorderedSubarray(new int[]{7, 9, 10, 8, 11})
-        );        
+        );
     }
 }
diff --git a/interview_prep/algorithm/java17/src/test/java/hoa/can/code/SubArrGivenSumTest.java b/interview_prep/algorithm/java17/src/test/java/hoa/can/code/SubArrGivenSumTest.java
@@ -3,6 +3,8 @@
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
 
+import hoa.can.code.ez.SubArrGivenSum;
+
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
 import java.util.ArrayList;
@@ -18,6 +20,10 @@ public void test() {
                 res,
                 hoa.can.code.ez.SubArrGivenSum.subarraySum(new int[] { 1,2 }, 1, 2)
         );
+        assertEquals(
+                res,
+                hoa.can.code.ez.SubArrGivenSum.subarraySum(SubArrGivenSum.SLIDING_WINDOWS, new int[] { 1,2 }, 1, 2)
+        );
     }
     @Test
     @DisplayName("https://practice.geeksforgeeks.org/problems/subarray-with-given-sum-1587115621/1")
@@ -29,8 +35,12 @@ public void test2() {
                 res,
                 hoa.can.code.ez.SubArrGivenSum.subarraySum(new int[] { 1,2 }, 1, 1)
         );
+        assertEquals(
+                res,
+                hoa.can.code.ez.SubArrGivenSum.subarraySum(SubArrGivenSum.SLIDING_WINDOWS, new int[] { 1,2 }, 1, 1)
+        );
     }
-    
+
     @Test
     @DisplayName("https://practice.geeksforgeeks.org/problems/subarray-with-given-sum-1587115621/1")
     public void test3() {
@@ -41,5 +51,9 @@ public void test3() {
                 res,
                 hoa.can.code.ez.SubArrGivenSum.subarraySum(new int[] { 1,2 }, 1, 2)
         );
-    }    
+        assertEquals(
+                res,
+                hoa.can.code.ez.SubArrGivenSum.subarraySum(SubArrGivenSum.SLIDING_WINDOWS, new int[] { 1,2 }, 1, 2)
+        );
+    }
 }