EPI: array game, array duplicate removal (py, cpp)

Author: jsgoller1

elements-of-programming-interviews/cpp/advance_by_offsets.cc

@@ -2,8 +2,17 @@
 
 #include "test_framework/generic_test.h"
 using std::vector;
-bool CanReachEnd(const vector<int>& max_advance_steps) {
-  // TODO - you fill in here.
+bool CanReachEnd(const vector<int>& arr) {
+  int best = arr[0];
+  for (int curr = 0; curr < arr.size(); curr++) {
+    if (best >= arr.size() - 1) {
+      return true;
+    }
+    if (curr > best) {
+      return false;
+    }
+    best = (curr + arr[curr] > best) ? curr + arr[curr] : best;
+  }
   return true;
 }
 

elements-of-programming-interviews/cpp/sorted_array_remove_dups.cc

@@ -5,8 +5,19 @@
 using std::vector;
 // Returns the number of valid entries after deletion.
 int DeleteDuplicates(vector<int>* A_ptr) {
-  // TODO - you fill in here.
-  return 0;
+  vector<int>& A = *A_ptr;
+  if (A.size() == 1 || A.size() == 0) {
+    return A.size();
+  }
+
+  int target = 1;
+  for (int i = 1; i < A.size(); i++) {
+    if (A[i - 1] != A[i]) {
+      A[target] = A[i];
+      target++;
+    }
+  }
+  return target;
 }
 vector<int> DeleteDuplicatesWrapper(TimedExecutor& executor, vector<int> A) {
   int end = executor.Run([&] { return DeleteDuplicates(&A); });

elements-of-programming-interviews/problem_mapping.js

@@ -228,29 +228,29 @@ problem_mapping = {
         },
         "5.04 Advancing through an array": {
             "C++: advance_by_offsets.cc": {
-                "passed": 0,
+                "passed": 2004,
                 "total": 2004
             },
             "Java: AdvanceByOffsets.java": {
                 "passed": 0,
                 "total": 2004
             },
             "Python: advance_by_offsets.py": {
-                "passed": 0,
+                "passed": 2004,
                 "total": 2004
             }
         },
         "5.05 Delete duplicates from a sorted array": {
             "C++: sorted_array_remove_dups.cc": {
-                "passed": 0,
+                "passed": 2003,
                 "total": 2003
             },
             "Java: SortedArrayRemoveDups.java": {
                 "passed": 0,
                 "total": 2003
             },
             "Python: sorted_array_remove_dups.py": {
-                "passed": 0,
+                "passed": 2003,
                 "total": 2003
             }
         },

elements-of-programming-interviews/python/advance_by_offsets.py

@@ -4,8 +4,15 @@
 
 
 def can_reach_end(A: List[int]) -> bool:
-    # TODO - you fill in here.
-    return True
+    best = A[0]
+    curr = 0
+    for dist in A:
+        if (curr > best):
+            return False
+        if (best >= len(A)-1):
+            return True
+        best = max(curr + A[curr], best)
+        curr += 1
 
 
 if __name__ == '__main__':

elements-of-programming-interviews/python/sorted_array_remove_dups.py

@@ -7,8 +7,14 @@
 
 # Returns the number of valid entries after deletion.
 def delete_duplicates(A: List[int]) -> int:
-    # TODO - you fill in here.
-    return 0
+    i = 1
+    target = 1
+    while i < len(A):
+        if A[i-1] != A[i]:
+            A[target] = A[i]
+            target += 1
+        i += 1
+    return target
 
 
 @enable_executor_hook