cpp/recursion/array_max

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Using tail recursion (i.e. where you do some work on the way down the recursion and then just return the answer back up)
create a method <tt>amax()</tt>
that finds the maximum element in an array of non-negative integers.

Return -1 if the list is empty.

Consider carefully what data needs to be communicated as you recurse down the array and then as you return back up the array. If you believe it necessary, define a helper function.

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Copied from problem cpp/recursion/array_max_head (author: redekopp@usc.edu)
Copied from problem cpp/recursion/list_max (author: daveagp@gmail.com)

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Choices
json list of string, bool pairs
e.g. [["good", true], ["bad", false]]

Correct answer
Template / Reference solution

Template / Reference solution

#include <iostream>
#include <algorithm>
using namespace std;

// You can prototype a helper function here if you need it
\[
int amax_helper(int* array, int len, int mymax);

\show:
void dummy(); // replace me if needed, else just leave me alone
]\

// This is the primary max() function that the user should call
int amax(int* array, int len)
{
\[
return amax_helper(array, len, -1);

]\
}

// You can write your helper function here if you need it
\[
int amax_helper(int* array, int len, int mymax)
{
if(len == 0)
return mymax;
else {
return amax_helper(array+1, len-1, max(mymax, array[0]));
}
}
\show:
void dummy(){}; // replace me if needed, else just leave me alone
]\

int main() {
int len;
cin >> len;
int* data = new int[len];
for(int i=0; i < len; i++){
cin >> data[i];
}
cout << amax(data, len);
return 0;
}

Java test suite
See manual

C++ test suite
json list of stdin/args tests
e.g. [{"stdin":"hi", "args":["4", "5"]}, {"stdin":"noargs"}]
to just run once with no input use [{}]

[
{"stdin": "3 1 0 3"},
{"stdin": "3 3 0 1"},
{"stdin": "3 1 3 0"},
{"stdin": "0 "},
{"stdin": "5 9 4 4 0 19"},
{"stdin": "5 2923 2 20 43 298"}
]

C++ test suite
See manual

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Property	Value
Description html markup shown to student	Using tail recursion (i.e. where you do some work on the way down the recursion and then just return the answer back up) create a method <tt>amax()</tt> that finds the maximum element in an array of non-negative integers. <p> <strong>Return -1 if the list is empty.</strong> <p> Consider carefully what data needs to be communicated as you recurse down the array and then as you return back up the array.<br><strong>If you believe it necessary, define a helper function.</strong>
Epilogue html markup shown when solved	remove
Public permissions	remove
Remarks Comments, history, license, etc.	Copied from problem cpp/recursion/array_max_head (author: redekopp@usc.edu) Copied from problem cpp/recursion/list_max (author: daveagp@gmail.com) remove
Engine
Choices json list of string, bool pairs e.g. `[["good", true], ["bad", false]]`
Correct answer
Template / Reference solution
Template / Reference solution	#include <iostream> #include <algorithm> using namespace std; // You can prototype a helper function here if you need it \[ int amax_helper(int* array, int len, int mymax); \show: void dummy(); // replace me if needed, else just leave me alone ]\ // This is the primary max() function that the user should call int amax(int* array, int len) { \[ return amax_helper(array, len, -1); ]\ } // You can write your helper function here if you need it \[ int amax_helper(int* array, int len, int mymax) { if(len == 0) return mymax; else { return amax_helper(array+1, len-1, max(mymax, array[0])); } } \show: void dummy(){}; // replace me if needed, else just leave me alone ]\ int main() { int len; cin >> len; int* data = new int[len]; for(int i=0; i < len; i++){ cin >> data[i]; } cout << amax(data, len); return 0; }
Java test suite See manual
C++ test suite json list of stdin/args tests e.g. `[{"stdin":"hi", "args":["4", "5"]}, {"stdin":"noargs"}]` to just run once with no input use `[{}]`	[ {"stdin": "3 1 0 3"}, {"stdin": "3 3 0 1"}, {"stdin": "3 1 3 0"}, {"stdin": "0 "}, {"stdin": "5 9 4 4 0 19"}, {"stdin": "5 2923 2 20 43 298"} ]
C++ test suite See manual
Forbidden substrings json list of strings e.g. `["for","while"]`	["for", "while", "do"] remove
Solution visibility	remove
Java imports json list of importables e.g. `["java.util.*"]`	remove
Override Java classname else defaults to websheet name	remove
Dependent on other websheets? json list of websheet names in this folder e.g. `["DataStructure"]`	remove
Is example? i.e., just a demo	remove
Add compiler flag(s) json list of flags e.g. `["-Wno-unused-variable"]`	remove
Remove default compiler flag(s) json list of flags see default_cppflags e.g. `["-Wno-write-strings"]`	remove

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