Initial commit

2015/puzzle-25-01.cc

@@ -0,0 +1,49 @@
+#include <cstdint>
+#include <string>
+#include <iostream>
+
+std::uint64_t lcg(std::uint64_t val)
+{
+    return (val * 252533) % 33554393;
+}
+
+int main()
+{
+    std::string line;
+    std::getline(std::cin, line);
+
+    using namespace std::string_literals;
+    auto line_begin{"To continue, please consult the code grid in the manual.  Enter the code at row "s};
+    auto line_middle{", column "s};
+    auto line_end{"."s};
+
+    assert(line.substr(0, line_begin.size()) == line_begin);
+    line = line.substr(line_begin.size());
+    std::size_t idx = 0;
+    unsigned long target_row = std::stoul(line, &idx);
+    line = line.substr(idx);
+    assert(line.substr(0, line_middle.size()) == line_middle);
+    line = line.substr(line_middle.size());
+    unsigned long target_column = std::stoul(line, &idx);
+    line = line.substr(idx);
+    assert(line == line_end);
+
+    unsigned long row{1};
+    unsigned long column{1};
+    std::uint64_t num{20151125};
+    while (row != target_row || column != target_column) {
+        if (row == 1) {
+            row = column + 1;
+            column = 1;
+        }
+        else {
+            --row;
+            ++column;
+        }
+        num = lcg(num);
+    }
+
+    std::cout << "Target row " << target_row << " column " << target_column << '\n';
+    std::cout << "Row " << row << " column " << column << " num " << num << '\n';
+    return 0;
+}