From 96254947699986c59f0dc63d69fd4b76bd3ed43e Mon Sep 17 00:00:00 2001
From: Sebastiano Tronto <sebastiano@tronto.net>
Date: Mon, 6 Jul 2026 19:08:08 +0200
Subject: Initial commit

---
 .../mex_grid_construction_3419.cpp                 | 30 ++++++++++++++++++++++
 1 file changed, 30 insertions(+)
 create mode 100644 01_introductory_problems/mex_grid_construction_3419.cpp

(limited to '01_introductory_problems/mex_grid_construction_3419.cpp')

diff --git a/01_introductory_problems/mex_grid_construction_3419.cpp b/01_introductory_problems/mex_grid_construction_3419.cpp
new file mode 100644
index 0000000..feb1171
--- /dev/null
+++ b/01_introductory_problems/mex_grid_construction_3419.cpp
@@ -0,0 +1,30 @@
+#include <algorithm>
+#include <bitset>
+#include <iostream>
+#include <vector>
+
+int firstzero(const std::bitset<200>& b) {
+	for (int i = 0; i < 200; i++)
+		if (!b.test(i))
+			return i;
+	return -1;
+}
+
+int next(int i, int j, std::vector<std::bitset<200>>& col,
+    std::vector<std::bitset<200>>& row) {
+	int r = firstzero(row[i] | col[j]);
+	row[i][r] = col[j][r] = 1;
+	return r;
+}
+
+int main() {
+	int n;
+	std::cin >> n;
+	std::vector<std::bitset<200>> col(n), row(n);
+
+	for (int i = 0; i < n; i++) {
+		for (int j = 0; j < n; j++)
+			std::cout << next(i, j, col, row) << " ";
+		std::cout << "\n";
+	}
+}
-- 
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