Стек и очередь: Сортировочная станция

src/23oct25/sorting_station.c

@@ -0,0 +1,136 @@
+#include <ctype.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "../stack/stack.h"
+
+int getPrecedence(char op)
+{
+    if (op == '*' || op == '/') {
+        return 2;
+    }
+
+    if (op == '+' || op == '-') {
+        return 1;
+    }
+
+    return 0;
+}
+
+void infixToPostfix(const char* infix, char* postfix)
+{
+    struct Stack* stack = new();
+    int i = 0;
+    int j = 0;
+    int topVal = 0;
+    int val = 0;
+
+    while (infix[i] != '\0') {
+        char token = infix[i];
+
+        if (isspace(token)) {
+            i++;
+            continue;
+        }
+
+        if (isdigit(token)) {
+            while (isdigit(infix[i])) {
+                postfix[j++] = infix[i++];
+            }
+            postfix[j++] = ' ';
+            continue;
+        }
+
+        if (token == '(') {
+            stack = push(stack, token);
+        } else if (token == ')') {
+            while (stack != NULL && peek(stack) != '(') {
+                stack = pop(stack, &topVal);
+                postfix[j++] = (char)topVal;
+                postfix[j++] = ' ';
+            }
+
+            if (stack != NULL && peek(stack) == '(') {
+                stack = pop(stack, &topVal);
+            }
+        } else if (token == '+' || token == '-' || token == '*' || token == '/') {
+            while (stack != NULL) {
+                int top = peek(stack);
+                if (top == '(') {
+                    break;
+                }
+
+                if (getPrecedence((char)top) >= getPrecedence(token)) {
+                    stack = pop(stack, &val);
+                    postfix[j++] = (char)val;
+                    postfix[j++] = ' ';
+                } else {
+                    break;
+                }
+            }
+
+            stack = push(stack, token);
+        }
+
+        i++;
+    }
+
+    while (stack != NULL) {
+        stack = pop(stack, &val);
+        postfix[j++] = (char)val;
+        postfix[j++] = ' ';
+    }
+
+    if (j > 0 && postfix[j - 1] == ' ') {
+        postfix[j - 1] = '\0';
+    } else {
+        postfix[j] = '\0';
+    }
+
+    delete(stack);
+}
+
+int main(void)
+{
+    char* infix = NULL;
+    char* postfix = NULL;
+    size_t capacity = 0;
+    size_t length = 0;
+    int ch = 0;
+
+    while ((ch = getchar()) != '\n' && ch != EOF) {
+        if (length + 1 >= capacity) {
+            if (capacity == 0) {
+                capacity = 16;
+            } else {
+                capacity *= 2;
+            }
+
+            infix = realloc(infix, capacity * sizeof(char));
+            if (infix == NULL) {
+                return 1;
+            }
+        }
+        infix[length++] = (char)ch;
+    }
+
+    if (infix != NULL) {
+        infix[length] = '\0';
+    } else {
+        infix = calloc(1, sizeof(char));
+    }
+
+    postfix = calloc(length * 2 + 1, sizeof(char));
+    if (postfix == NULL) {
+        free(infix);
+        return 1;
+    }
+
+    infixToPostfix(infix, postfix);
+    printf("%s\n", postfix);
+
+    free(infix);
+    free(postfix);
+
+    return 0;
+}

src/stack/stack.c

@@ -0,0 +1,53 @@
+#include <stdlib.h>
+#include "stack.h"
+
+struct Stack {
+    int value;
+    struct Stack* next;
+};
+
+struct Stack* push(struct Stack* stack, int value)
+{
+    struct Stack* newStack = malloc(sizeof(struct Stack));
+
+    if (!newStack)
+        return NULL;
+
+    newStack->value = value;
+    newStack->next = stack;
+    return newStack;
+}
+
+struct Stack* pop(struct Stack* stack, int* value) 
+{
+    if (stack == NULL)
+        return NULL;
+
+    struct Stack* temp = stack->next;
+    *value = stack->value;
+    free(stack);
+    return temp;
+}
+
+int peek(struct Stack* stack) 
+{
+    if (stack == NULL)
+        return -1;
+
+    return stack->value;
+}
+
+struct Stack* new(void) 
+{
+    return NULL;
+}
+
+void delete(struct Stack* stack) 
+{
+    while (stack != NULL) {
+        struct Stack* temp = stack;
+        stack = stack->next;
+        free(temp);
+    }
+}
+

src/stack/stack.h

@@ -0,0 +1,18 @@
+#pragma once 
+
+struct Stack;
+
+// Создает новый стек с NULL
+struct Stack* new(void);
+
+// Кладет элемент на стек и возвращает измененный стек
+struct Stack* push(struct Stack* stack, int value);
+
+// Берет элемент со стек, возвращает измененный стек, сохраняет удаленное значение в аргумент value
+struct Stack* pop(struct Stack* stack, int* value);
+
+// Возвращает верхний элемент стека
+int peek(struct Stack* stack);
+
+// Удаляет весь стек
+void delete(struct Stack* stack);