Solve 'Scramblies' kata (#3)

Author: borisskert

include/scramblies/scramble.h

@@ -0,0 +1,8 @@
+#ifndef CPP_KATAS_SCRAMBLE_H
+#define CPP_KATAS_SCRAMBLE_H
+
+#include<string>
+
+bool scramble(const std::string& s1, const std::string& s2);
+
+#endif //CPP_KATAS_SCRAMBLE_H

src/scramblies/scramble.cpp

@@ -0,0 +1,63 @@
+#include<string>
+#include <unordered_map>
+#include <algorithm>
+
+/*
+ * https://www.codewars.com/kata/55c04b4cc56a697bb0000048/train/cpp
+ */
+
+class Scramblies {
+private:
+    const std::unordered_map<char, int> _counts;
+
+    explicit Scramblies(std::unordered_map<char, int> counts) : _counts(std::move(counts)) {}
+
+public:
+    [[nodiscard]] Scramblies increaseAll(const std::string &s) const;
+
+    [[nodiscard]] Scramblies decreaseAll(const std::string &s) const;
+
+    [[nodiscard]] bool allNonNegative() const;
+
+    static Scramblies empty() {
+        return Scramblies(std::unordered_map<char, int>(0));
+    }
+};
+
+bool scramble(const std::string &s1, const std::string &s2) {
+    return Scramblies::empty()
+            .increaseAll(s1)
+            .decreaseAll(s2)
+            .allNonNegative();
+}
+
+Scramblies Scramblies::increaseAll(const std::string &s) const {
+    std::unordered_map<char, int> counts = this->_counts;
+
+    for (const char c: s) {
+        int count = counts[c];
+        counts[c] = count + 1;
+    }
+
+    return Scramblies(counts);
+}
+
+Scramblies Scramblies::decreaseAll(const std::string &s) const {
+    std::unordered_map<char, int> counts = this->_counts;
+
+    for (const char c: s) {
+        int count = counts[c];
+        counts[c] = count - 1;
+    }
+
+    return Scramblies(counts);
+}
+
+bool Scramblies::allNonNegative() const {
+    return std::all_of(
+            this->_counts.begin(),
+            this->_counts.end(),
+            [&](const std::pair<const char, int> &item) {
+                return item.second >= 0;
+            });
+}

test/scramblies/scramble_test.cpp

@@ -0,0 +1,19 @@
+#include <igloo/igloo_alt.h>
+#include "scramblies/scramble.h"
+
+using namespace igloo;
+
+Describe(Scramble) {
+    It(BasicTests) {
+        Assert::That(scramble("rkqodlw", "world"), Equals(true));
+        Assert::That(scramble("cedewaraaossoqqyt", "codewars"), Equals(true));
+        Assert::That(scramble("katas", "steak"), Equals(false));
+        Assert::That(scramble("scriptjavx", "javascript"), Equals(false));
+        Assert::That(scramble("scriptingjava", "javascript"), Equals(true));
+        Assert::That(scramble("scriptsjava", "javascript"), Equals(true));
+        Assert::That(scramble("javscripts", "javascript"), Equals(false));
+        Assert::That(scramble("aabbcamaomsccdd", "commas"), Equals(true));
+        Assert::That(scramble("commas", "commas"), Equals(true));
+        Assert::That(scramble("sammoc", "commas"), Equals(true));
+    }
+};