1 files changed, 71 insertions, 0 deletions
diff --git a/src/utils.cc b/src/utils.cc
new file mode 100644
index 0000000..009754b
--- /dev/null
+++ b/src/utils.cc
@@ -0,0 +1,71 @@
+#include "utils.h"
+#include "json.hpp"
+#include <sstream>
+#include <fstream>
+#include <string>
+#include <vector>
+#include <filesystem>
+#include <stdexcept>
+#include <map>
+
+nlohmann::json utils::loadJson(const std::string& path) {
+    std::ifstream f(path);
+    nlohmann::json j;
+    f >> j;
+    return j;
+}
+
+void utils::saveJson(const nlohmann::json& data, const std::string& path) {
+    std::ofstream f(path);
+    f << std::setw(4) << data << std::endl;
+}
+
+/*std::string utils::join(std::vector<std::string> parts, std::string joiner) {
+    std::stringstream out;
+    bool isFirst = true;
+    for(std::string p : parts) {
+        if(! isFirst) {
+            out << joiner;
+        }
+        isFirst = false;
+        out << p;
+    }
+    return out.str();
+}*/
+
+// Accepts coins formatted "X Yp" where X is an integer and Y is any of c, s, e, g, p.
+int utils::coins2copper(const std::string& coins) {
+    int num = std::stoi(coins.substr(0, coins.find(" ")));
+    std::string denomination(coins.substr(coins.find(" ") + 1));
+    if(! cpValue.contains(denomination)) {
+        throw std::invalid_argument("Unknown coin type: " + denomination);
+    }
+    return num * cpValue.at(denomination);
+}
+
+// Greedily selects highest coin values to minimize total number of coins
+// Returns a vector of pairs mapping coin type to coint
+std::vector<std::pair<std::string, int>> utils::copper2coins(int coppers) {
+    std::vector<std::pair<std::string, int>> ret;
+    while(coppers > 0) {
+        // Find the largest denomination in cpValue under coppers
+        std::pair<std::string, int> largest("", 0);
+        for(auto pair : cpValue) {
+            if(pair.second <= coppers && pair.second > largest.second) {
+                largest = pair;
+            }
+        }
+        std::pair<std::string, int> amnt(largest.first, coppers / largest.second);
+        coppers -= amnt.second * largest.second;
+        ret.push_back(amnt);
+    }
+    return ret;
+}
+
+std::string utils::getCostString(int coppers) {
+    std::vector<std::string> parts;
+    for(auto pair : utils::copper2coins(coppers)) {
+        parts.push_back(std::to_string(pair.second) + " " + pair.first);
+    }
+    return utils::join(parts, ", ");
+}