upload

7.1/A.cpp

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+#include <iostream>
+#include <string>
+#include <vector>
+
+typedef long long ll;
+
+void GrayCode(ll n) {
+  if (n <= 0) {
+    return;
+  }
+
+  std::vector<std::string> code;
+
+  code.push_back("0");
+  code.push_back("1");
+
+  ll i, j;
+
+  for (i = 2; i < (1 << n); i = i << 1) {
+    for (j = i - 1; j >= 0; j--) {
+      code.push_back(code[j]);
+    }
+    for (j = 0; j < i; j++) {
+      code[j] = "0" + code[j];
+    }
+    for (j = i; j < 2 * i; j++) {
+      code[j] = "1" + code[j];
+    }
+  }
+
+  for (i = 0; i < code.size(); i++)
+    std::cout << code[i] << std::endl;
+}
+
+int main() {
+  ll n;
+  std::cin >> n;
+  GrayCode(n);
+  return 0;
+}

7.1/B.py

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+def lz78(string: str) -> None:
+    buffer = ''
+    enc_dict: dict[str, int] = {}
+    for char in string:
+        comb = buffer + char
+        if comb in enc_dict:
+            buffer += char
+        else:
+            if buffer in enc_dict:
+                print(enc_dict[buffer], char)
+            else:
+                print(0, char)
+            enc_dict[comb] = len(enc_dict) + 1
+            buffer = ""
+
+    if buffer:
+        if buffer in enc_dict:
+            print(str(enc_dict[buffer]) + ' \0')
+        else:
+            print(enc_dict[buffer[:-1]], buffer[-1])
+
+
+
+def main():
+    s = input()
+    lz78(s)
+
+if __name__ == "__main__":
+    main()
+

7.1/E.py

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+import dataclasses
+
+@dataclasses.dataclass
+class Segment:
+    l: float
+    r: float
+
+def find_alphabet(s: str) -> list[str]:
+    alphabet = []
+    for x in s:
+        if x not in alphabet:
+            alphabet.append(x)
+    return alphabet
+
+def find_probabilities(s: str, alphabet: list[str]) -> dict[str, Segment]:
+    count: dict[str, int] = {}
+    for x in s:
+        if x not in count:
+            count[x] = 0
+        count[x] += 1
+
+    left = 0.0
+    slice = 1.0 / len(s)
+    segments: dict[str, Segment] = {}
+
+    for x in sorted(alphabet):
+        segments[x] = Segment(left,left + (slice * count[x]))
+        left += slice * count[x]
+
+    return segments
+
+
+def arithmetic_coding(s: str) -> float:
+    alphabet = find_alphabet(s)
+    probabilities = find_probabilities(s, alphabet)
+
+    left = 0.0
+    right = 1.0
+
+    for x in s:
+        new_left = left + (right - left) * probabilities[x].l
+        new_right = left + (right - left) * probabilities[x].r
+
+        left = new_left
+        right = new_right
+
+    return left
+
+
+
+
+def main():
+    s = input()
+    print(round(arithmetic_coding(s), 6))
+
+
+if __name__ == "__main__":
+    main()