From 423ceb18f4c46e7597c5f7462b97bc5c28e380ca Mon Sep 17 00:00:00 2001
From: colinleach <colin.leach@comcast.net>
Date: Mon, 17 Apr 2023 18:10:21 -0700
Subject: [PATCH 1/6] half-done nth-prime example

---
 config.json                                   | 12 +++++++
 .../practice/nth-prime/.docs/instructions.md  |  7 ++++
 .../practice/nth-prime/.meta/config.json      | 17 ++++++++++
 exercises/practice/nth-prime/.meta/tests.toml | 25 ++++++++++++++
 exercises/practice/nth-prime/nth-prime.R      | 33 +++++++++++++++++++
 exercises/practice/nth-prime/test_nth-prime.R | 32 ++++++++++++++++++
 6 files changed, 126 insertions(+)
 create mode 100644 exercises/practice/nth-prime/.docs/instructions.md
 create mode 100644 exercises/practice/nth-prime/.meta/config.json
 create mode 100644 exercises/practice/nth-prime/.meta/tests.toml
 create mode 100644 exercises/practice/nth-prime/nth-prime.R
 create mode 100644 exercises/practice/nth-prime/test_nth-prime.R

diff --git a/config.json b/config.json
index 98859d1f..0f0b9777 100644
--- a/config.json
+++ b/config.json
@@ -485,6 +485,18 @@
           "loops",
           "math"
         ]
+      },
+      {
+        "slug": "nth-prime",
+        "name": "Nth Prime",
+        "uuid": "96b66be6-7e08-4ea6-8684-c21d3ce32900",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 1,
+        "status": "wip",
+        "topics": [
+          "math"
+        ]
       }
     ]
   },
diff --git a/exercises/practice/nth-prime/.docs/instructions.md b/exercises/practice/nth-prime/.docs/instructions.md
new file mode 100644
index 00000000..065e323a
--- /dev/null
+++ b/exercises/practice/nth-prime/.docs/instructions.md
@@ -0,0 +1,7 @@
+# Instructions
+
+Given a number n, determine what the nth prime is.
+
+By listing the first six prime numbers: 2, 3, 5, 7, 11, and 13, we can see that the 6th prime is 13.
+
+If your language provides methods in the standard library to deal with prime numbers, pretend they don't exist and implement them yourself.
diff --git a/exercises/practice/nth-prime/.meta/config.json b/exercises/practice/nth-prime/.meta/config.json
new file mode 100644
index 00000000..d84dfd7e
--- /dev/null
+++ b/exercises/practice/nth-prime/.meta/config.json
@@ -0,0 +1,17 @@
+{
+  "authors": [],
+  "files": {
+    "solution": [
+      "nth-prime.R"
+    ],
+    "test": [
+      "test_nth-prime.R"
+    ],
+    "example": [
+      ".meta/example.R"
+    ]
+  },
+  "blurb": "Given a number n, determine what the nth prime is.",
+  "source": "A variation on Problem 7 at Project Euler",
+  "source_url": "https://projecteuler.net/problem=7"
+}
diff --git a/exercises/practice/nth-prime/.meta/tests.toml b/exercises/practice/nth-prime/.meta/tests.toml
new file mode 100644
index 00000000..daccec42
--- /dev/null
+++ b/exercises/practice/nth-prime/.meta/tests.toml
@@ -0,0 +1,25 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[75c65189-8aef-471a-81de-0a90c728160c]
+description = "first prime"
+
+[2c38804c-295f-4701-b728-56dea34fd1a0]
+description = "second prime"
+
+[56692534-781e-4e8c-b1f9-3e82c1640259]
+description = "sixth prime"
+
+[fce1e979-0edb-412d-93aa-2c744e8f50ff]
+description = "big prime"
+
+[bd0a9eae-6df7-485b-a144-80e13c7d55b2]
+description = "there is no zeroth prime"
diff --git a/exercises/practice/nth-prime/nth-prime.R b/exercises/practice/nth-prime/nth-prime.R
new file mode 100644
index 00000000..1431ed67
--- /dev/null
+++ b/exercises/practice/nth-prime/nth-prime.R
@@ -0,0 +1,33 @@
+
+prime <- function(n) {
+  if (n < 1) stop("n must be a positive integer")
+  
+  known <- vector("integer", n)
+  is_prime <- function(candidate) {
+    sqrt_candidate <- sqrt(candidate)
+    for (item in known) {
+      if (item > sqrt_candidate) return(TRUE)
+      if (candidate %% item == 0) return(FALSE)
+      TRUE
+    }
+  }
+  
+  known[1] <- 2
+  known[2] <- 3
+  known_count <- 2
+  number <- 6
+  while (TRUE) {
+    if (known_count >= n) return(known[n])
+    if (is_prime(number - 1)) {
+      known_count <- known_count + 1
+      known[known_count] <- number - 1
+    }
+    if (known_count >= n) return(known[n])
+    if (is_prime(number + 1)) {
+      known_count <- known_count + 1
+      known[known_count] <- number + 1
+    }
+    number <- number + 6
+  }
+  
+}
\ No newline at end of file
diff --git a/exercises/practice/nth-prime/test_nth-prime.R b/exercises/practice/nth-prime/test_nth-prime.R
new file mode 100644
index 00000000..991f99d0
--- /dev/null
+++ b/exercises/practice/nth-prime/test_nth-prime.R
@@ -0,0 +1,32 @@
+source("./nth-prime.R")
+library(testthat)
+
+context("nth-prime")
+
+test_that("first prime", {
+  n <- 1
+  expect_equal(prime(n), 2)
+})
+
+test_that("second prime", {
+  n <- 2
+  expect_equal(prime(n), 3)
+})
+
+test_that("sixth prime", {
+  n <- 6
+  expect_equal(prime(n), 13)
+})
+
+test_that("big prime", {
+  n <- 10001
+  expect_equal(prime(n), 104743)
+})
+
+test_that("there is no zeroth prime", {
+  n <- 0
+  expect_error(prime(n))
+})
+
+
+message("All tests passed for exercise: luhn")

From 7ce5ff3d42adaff1564ab4a7e2844cc48918c0ef Mon Sep 17 00:00:00 2001
From: colinleach <colin.leach@comcast.net>
Date: Mon, 17 Apr 2023 23:33:48 -0700
Subject: [PATCH 2/6] working example code

---
 exercises/practice/nth-prime/.meta/example.R | 35 ++++++++++++++++++++
 exercises/practice/nth-prime/nth-prime.R     | 34 ++-----------------
 2 files changed, 37 insertions(+), 32 deletions(-)
 create mode 100644 exercises/practice/nth-prime/.meta/example.R

diff --git a/exercises/practice/nth-prime/.meta/example.R b/exercises/practice/nth-prime/.meta/example.R
new file mode 100644
index 00000000..a4df5351
--- /dev/null
+++ b/exercises/practice/nth-prime/.meta/example.R
@@ -0,0 +1,35 @@
+# Not the prettiest code, but it passes the tests reasonably quickly
+
+prime <- function(n) {
+  if (n < 1) stop("n must be a positive integer")
+  
+  known <- vector("integer", n) # to store primes as we find them
+  
+  is_prime <- function(candidate) {
+    sqrt_candidate <- sqrt(candidate)
+    for (item in known) {
+      if (item > sqrt_candidate) return(TRUE)
+      if (candidate %% item == 0) return(FALSE)
+      TRUE
+    }
+  }
+  
+  # Early primes are added explicitly:
+  known[1] <- 2
+  known[2] <- 3
+  
+  # Prime candidates are 6i +/- 1 : 5, 7, 11, 13...
+  # Python does this with `itertools.choice()`. Is there an equivalent in R?
+  known_count <- 2
+  number <- 6
+  while (TRUE) {
+    for (candidate in c(number - 1, number + 1)) {
+      if (known_count >= n) return(known[n]) # result!
+      if (is_prime(candidate)) {
+        known_count <- known_count + 1
+        known[known_count] <- candidate
+      }
+    }
+    number <- number + 6
+  }
+}
\ No newline at end of file
diff --git a/exercises/practice/nth-prime/nth-prime.R b/exercises/practice/nth-prime/nth-prime.R
index 1431ed67..77640559 100644
--- a/exercises/practice/nth-prime/nth-prime.R
+++ b/exercises/practice/nth-prime/nth-prime.R
@@ -1,33 +1,3 @@
-
 prime <- function(n) {
-  if (n < 1) stop("n must be a positive integer")
-  
-  known <- vector("integer", n)
-  is_prime <- function(candidate) {
-    sqrt_candidate <- sqrt(candidate)
-    for (item in known) {
-      if (item > sqrt_candidate) return(TRUE)
-      if (candidate %% item == 0) return(FALSE)
-      TRUE
-    }
-  }
-  
-  known[1] <- 2
-  known[2] <- 3
-  known_count <- 2
-  number <- 6
-  while (TRUE) {
-    if (known_count >= n) return(known[n])
-    if (is_prime(number - 1)) {
-      known_count <- known_count + 1
-      known[known_count] <- number - 1
-    }
-    if (known_count >= n) return(known[n])
-    if (is_prime(number + 1)) {
-      known_count <- known_count + 1
-      known[known_count] <- number + 1
-    }
-    number <- number + 6
-  }
-  
-}
\ No newline at end of file
+
+  }
\ No newline at end of file

From 5f2ecb9c810806cc96216e245c3337b233109f9c Mon Sep 17 00:00:00 2001
From: colinleach <colin.leach@comcast.net>
Date: Mon, 17 Apr 2023 23:39:37 -0700
Subject: [PATCH 3/6] minor tweaks

---
 config.json                                  | 6 ++++--
 exercises/practice/nth-prime/.meta/example.R | 2 +-
 exercises/practice/nth-prime/nth-prime.R     | 2 +-
 3 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/config.json b/config.json
index 0f0b9777..022addcb 100644
--- a/config.json
+++ b/config.json
@@ -492,11 +492,13 @@
         "uuid": "96b66be6-7e08-4ea6-8684-c21d3ce32900",
         "practices": [],
         "prerequisites": [],
-        "difficulty": 1,
+        "difficulty": 3,
         "status": "wip",
         "topics": [
+          "control_flow_conditionals",
+          "loops",
           "math"
-        ]
+         ]
       }
     ]
   },
diff --git a/exercises/practice/nth-prime/.meta/example.R b/exercises/practice/nth-prime/.meta/example.R
index a4df5351..e99f0e0b 100644
--- a/exercises/practice/nth-prime/.meta/example.R
+++ b/exercises/practice/nth-prime/.meta/example.R
@@ -32,4 +32,4 @@ prime <- function(n) {
     }
     number <- number + 6
   }
-}
\ No newline at end of file
+}
diff --git a/exercises/practice/nth-prime/nth-prime.R b/exercises/practice/nth-prime/nth-prime.R
index 77640559..ccd0dfe3 100644
--- a/exercises/practice/nth-prime/nth-prime.R
+++ b/exercises/practice/nth-prime/nth-prime.R
@@ -1,3 +1,3 @@
 prime <- function(n) {
 
-  }
\ No newline at end of file
+}

From aafe4f03c42ab4f64a4c4878f54fa53fec8c0bb3 Mon Sep 17 00:00:00 2001
From: colinleach <colin.leach@comcast.net>
Date: Mon, 17 Apr 2023 23:42:46 -0700
Subject: [PATCH 4/6] fixed typo

---
 exercises/practice/nth-prime/test_nth-prime.R | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/exercises/practice/nth-prime/test_nth-prime.R b/exercises/practice/nth-prime/test_nth-prime.R
index 991f99d0..3798a887 100644
--- a/exercises/practice/nth-prime/test_nth-prime.R
+++ b/exercises/practice/nth-prime/test_nth-prime.R
@@ -29,4 +29,4 @@ test_that("there is no zeroth prime", {
 })
 
 
-message("All tests passed for exercise: luhn")
+message("All tests passed for exercise: nth-prime")

From 6320bbd37cc8ba5427cab21d4b798ce473827338 Mon Sep 17 00:00:00 2001
From: colinleach <colin.leach@comcast.net>
Date: Tue, 18 Apr 2023 07:47:33 -0700
Subject: [PATCH 5/6] cleaned loop syntax, added author

---
 exercises/practice/nth-prime/.meta/config.json | 2 +-
 exercises/practice/nth-prime/.meta/example.R   | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/exercises/practice/nth-prime/.meta/config.json b/exercises/practice/nth-prime/.meta/config.json
index d84dfd7e..f48d6d91 100644
--- a/exercises/practice/nth-prime/.meta/config.json
+++ b/exercises/practice/nth-prime/.meta/config.json
@@ -1,5 +1,5 @@
 {
-  "authors": [],
+  "authors": ["colinleach"],
   "files": {
     "solution": [
       "nth-prime.R"
diff --git a/exercises/practice/nth-prime/.meta/example.R b/exercises/practice/nth-prime/.meta/example.R
index e99f0e0b..f00101f0 100644
--- a/exercises/practice/nth-prime/.meta/example.R
+++ b/exercises/practice/nth-prime/.meta/example.R
@@ -22,7 +22,7 @@ prime <- function(n) {
   # Python does this with `itertools.choice()`. Is there an equivalent in R?
   known_count <- 2
   number <- 6
-  while (TRUE) {
+  repeat {
     for (candidate in c(number - 1, number + 1)) {
       if (known_count >= n) return(known[n]) # result!
       if (is_prime(candidate)) {

From 66ab08e627024b2208eb6f5cc9b7de0c44ea74e3 Mon Sep 17 00:00:00 2001
From: colinleach <colin.leach@comcast.net>
Date: Tue, 18 Apr 2023 08:07:10 -0700
Subject: [PATCH 6/6] status to active

---
 config.json | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/config.json b/config.json
index 022addcb..c7893fa3 100644
--- a/config.json
+++ b/config.json
@@ -493,7 +493,7 @@
         "practices": [],
         "prerequisites": [],
         "difficulty": 3,
-        "status": "wip",
+        "status": "active",
         "topics": [
           "control_flow_conditionals",
           "loops",