From aeab9e7acad5017131cc93c5e3f96c1290f635fb Mon Sep 17 00:00:00 2001
From: Luke Holman <holman57@gmail.com>
Date: Mon, 23 Dec 2024 17:49:56 -0600
Subject: [PATCH] Add solution for 'Append and Delete' challenge in C

Implemented the 'appendAndDelete' function to determine whether a string transformation can be made in exactly a given number of operations. This includes logic for both optimal prefix matching and excess operations handling. Added supporting utility functions for input parsing and trimming.
---
 AppendAndDelete.c | 191 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 191 insertions(+)
 create mode 100644 AppendAndDelete.c

diff --git a/AppendAndDelete.c b/AppendAndDelete.c
new file mode 100644
index 0000000..bd16167
--- /dev/null
+++ b/AppendAndDelete.c
@@ -0,0 +1,191 @@
+#include <assert.h>
+#include <ctype.h>
+#include <limits.h>
+#include <math.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+char* readline();
+char* ltrim(char*);
+char* rtrim(char*);
+
+int parse_int(char*);
+
+/*
+ * Complete the 'appendAndDelete' function below.
+ *
+ * The function is expected to return a STRING.
+ * The function accepts following parameters:
+ *  1. STRING s
+ *  2. STRING t
+ *  3. INTEGER k
+ */
+
+/*
+ * To return the string from the function, you should either do static allocation or dynamic allocation
+ *
+ * For example,
+ * char* return_string_using_static_allocation() {
+ *     static char s[] = "static allocation of string";
+ *
+ *     return s;
+ * }
+ *
+ * char* return_string_using_dynamic_allocation() {
+ *     char* s = malloc(100 * sizeof(char));
+ *
+ *     s = "dynamic allocation of string";
+ *
+ *     return s;
+ * }
+ *
+ */
+char* appendAndDelete(char* s, char* t, int k) {
+    int sLen = strlen(s);
+    int tLen = strlen(t);
+
+    // Find the length of the common prefix
+    int commonLength = 0;
+    while (commonLength < sLen && commonLength < tLen && s[commonLength] == t[commonLength]) {
+        commonLength++;
+    }
+
+    // Calculate the minimum operations
+    int deletions = sLen - commonLength; // Remove remaining chars in `s`
+    int additions = tLen - commonLength; // Add remaining chars in `t`
+    int minOperations = deletions + additions;
+
+    // Check if the transformation is possible in exactly `k` operations
+    if (k < minOperations) {
+        return "No";
+    }
+
+    // Check if the excess operations are even, or if we can fully delete and rebuild
+    if ((k - minOperations) % 2 == 0 || k >= sLen + tLen) {
+        return "Yes";
+    }
+
+    return "No";
+}
+
+int main()
+{
+    FILE* fptr = fopen(getenv("OUTPUT_PATH"), "w");
+
+    char* s = readline();
+
+    char* t = readline();
+
+    int k = parse_int(ltrim(rtrim(readline())));
+
+    char* result = appendAndDelete(s, t, k);
+
+    fprintf(fptr, "%s\n", result);
+
+    fclose(fptr);
+
+    return 0;
+}
+
+char* readline() {
+    size_t alloc_length = 1024;
+    size_t data_length = 0;
+
+    char* data = malloc(alloc_length);
+
+    while (true) {
+        char* cursor = data + data_length;
+        char* line = fgets(cursor, alloc_length - data_length, stdin);
+
+        if (!line) {
+            break;
+        }
+
+        data_length += strlen(cursor);
+
+        if (data_length < alloc_length - 1 || data[data_length - 1] == '\n') {
+            break;
+        }
+
+        alloc_length <<= 1;
+
+        data = realloc(data, alloc_length);
+
+        if (!data) {
+            data = '\0';
+
+            break;
+        }
+    }
+
+    if (data[data_length - 1] == '\n') {
+        data[data_length - 1] = '\0';
+
+        data = realloc(data, data_length);
+
+        if (!data) {
+            data = '\0';
+        }
+    } else {
+        data = realloc(data, data_length + 1);
+
+        if (!data) {
+            data = '\0';
+        } else {
+            data[data_length] = '\0';
+        }
+    }
+
+    return data;
+}
+
+char* ltrim(char* str) {
+    if (!str) {
+        return '\0';
+    }
+
+    if (!*str) {
+        return str;
+    }
+
+    while (*str != '\0' && isspace(*str)) {
+        str++;
+    }
+
+    return str;
+}
+
+char* rtrim(char* str) {
+    if (!str) {
+        return '\0';
+    }
+
+    if (!*str) {
+        return str;
+    }
+
+    char* end = str + strlen(str) - 1;
+
+    while (end >= str && isspace(*end)) {
+        end--;
+    }
+
+    *(end + 1) = '\0';
+
+    return str;
+}
+
+int parse_int(char* str) {
+    char* endptr;
+    int value = strtol(str, &endptr, 10);
+
+    if (endptr == str || *endptr != '\0') {
+        exit(EXIT_FAILURE);
+    }
+
+    return value;
+}