From 32f31bd953c9d06abb3cd4518c3d512458178c71 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Andr=C3=A9=20Borba?= <andre.borbaaf2b@gmail.com>
Date: Sat, 19 Sep 2026 09:29:02 -0300
Subject: [PATCH] =?UTF-8?q?=F0=9F=9F=A2=20Port=20problem=201920=20(Build?=
 =?UTF-8?q?=20Array=20from=20Permutation)=20from=20Swift=20to=20C++23?=
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Replaces swift/1930.swift with
solutions/1901-2000/1920-build-array-from-permutation/.

The file was misnamed: its buildArray(nums) => nums[nums[i]] logic is
LeetCode 1920 "Build Array from Permutation", not 1930 ("Unique
Length-3 Palindromic Subsequences", an unrelated problem). Filed under
the number that matches the actual algorithm.
---
 .../README.md                                  | 11 +++++++++++
 .../solution.cpp                               | 18 ++++++++++++++++++
 .../solution.hpp                               | 10 ++++++++++
 .../1920-build-array-from-permutation/test.cpp |  8 ++++++++
 swift/1930.swift                               | 15 ---------------
 5 files changed, 47 insertions(+), 15 deletions(-)
 create mode 100644 solutions/1901-2000/1920-build-array-from-permutation/README.md
 create mode 100644 solutions/1901-2000/1920-build-array-from-permutation/solution.cpp
 create mode 100644 solutions/1901-2000/1920-build-array-from-permutation/solution.hpp
 create mode 100644 solutions/1901-2000/1920-build-array-from-permutation/test.cpp
 delete mode 100644 swift/1930.swift

diff --git a/solutions/1901-2000/1920-build-array-from-permutation/README.md b/solutions/1901-2000/1920-build-array-from-permutation/README.md
new file mode 100644
index 0000000..3654092
--- /dev/null
+++ b/solutions/1901-2000/1920-build-array-from-permutation/README.md
@@ -0,0 +1,11 @@
+# 1920. Build Array from Permutation
+
+[LeetCode problem 1920](https://leetcode.com/problems/build-array-from-permutation/)
+
+- **Difficulty**: Easy
+- **Tags**: array, simulation
+
+## Description
+
+Given a zero-indexed permutation `nums`, build an array `ans` where
+`ans[i] == nums[nums[i]]` for every `i`.
diff --git a/solutions/1901-2000/1920-build-array-from-permutation/solution.cpp b/solutions/1901-2000/1920-build-array-from-permutation/solution.cpp
new file mode 100644
index 0000000..ce052b4
--- /dev/null
+++ b/solutions/1901-2000/1920-build-array-from-permutation/solution.cpp
@@ -0,0 +1,18 @@
+#include "solution.hpp"
+
+#include <iterator>
+
+namespace leetcode::p1920 {
+
+std::vector<int> solve(const std::vector<int>& nums) {
+    std::vector<int> result;
+    result.reserve(nums.size());
+
+    for (int i = 0; i < std::ssize(nums); ++i) {
+        result.push_back(nums.at(static_cast<std::size_t>(nums.at(static_cast<std::size_t>(i)))));
+    }
+
+    return result;
+}
+
+} // namespace leetcode::p1920
diff --git a/solutions/1901-2000/1920-build-array-from-permutation/solution.hpp b/solutions/1901-2000/1920-build-array-from-permutation/solution.hpp
new file mode 100644
index 0000000..b00541c
--- /dev/null
+++ b/solutions/1901-2000/1920-build-array-from-permutation/solution.hpp
@@ -0,0 +1,10 @@
+#pragma once
+
+#include <vector>
+
+namespace leetcode::p1920 {
+
+// optimized: O(n) time, O(n) space — direct lookup, nums[nums[i]].
+std::vector<int> solve(const std::vector<int>& nums);
+
+} // namespace leetcode::p1920
diff --git a/solutions/1901-2000/1920-build-array-from-permutation/test.cpp b/solutions/1901-2000/1920-build-array-from-permutation/test.cpp
new file mode 100644
index 0000000..7939569
--- /dev/null
+++ b/solutions/1901-2000/1920-build-array-from-permutation/test.cpp
@@ -0,0 +1,8 @@
+#include <catch2/catch_test_macros.hpp>
+
+#include "solution.hpp"
+
+TEST_CASE("Problem 1920", "[p1920]") {
+    CHECK(leetcode::p1920::solve({0, 2, 1, 5, 3, 4}) == std::vector<int>{0, 1, 2, 4, 5, 3});
+    CHECK(leetcode::p1920::solve({5, 0, 1, 2, 3, 4}) == std::vector<int>{4, 5, 0, 1, 2, 3});
+}
diff --git a/swift/1930.swift b/swift/1930.swift
deleted file mode 100644
index a4d3c38..0000000
--- a/swift/1930.swift
+++ /dev/null
@@ -1,15 +0,0 @@
-func buildArray(_ nums: [Int]) -> [Int] {
-    var result: [Int] = []
-
-    for i in 0..<nums.count {
-        result.append(nums[nums[i]])
-    }
-
-    return result
-}
-
-let test1 = [0,2,1,5,3,4]
-let test2 = [5,0,1,2,3,4]
-
-print(buildArray(test1)) // [0,1,2,4,5,3]
-print(buildArray(test2)) // [4,5,0,1,2,3]
\ No newline at end of file