resort

Homework/SC/func.c

@@ -0,0 +1,65 @@
+#include "head.h"
+
+Stack get(Stack *l, int n) {
+  if (n > len(l))
+    exit(3);
+  int i;
+  for (i = 0; i < n; i++) {
+    l = l->next;
+  }
+  return *l;
+}
+
+Stack *add_head(Stack *l, double x) {
+  if (l == NULL) {
+    l = malloc(sizeof(Stack));
+    if (l == NULL)
+      exit(1);
+    l->x = x;
+    l->next = NULL;
+  }
+
+  if (l->x == 0.0) {
+    l->x = x;
+    l->next = NULL;
+    return l;
+  }
+
+  Stack *tmp = malloc(sizeof(Stack));
+  if (tmp == NULL)
+    exit(1);
+
+  tmp->next = l;
+  tmp->x = x;
+  return tmp;
+}
+
+void stack_print(Stack *l) {
+  while (l != NULL) {
+    printf("%lF\n", l->x);
+    l = l->next;
+  }
+}
+
+int len(Stack *l) {
+  int ans = 0;
+  while (l != NULL) {
+    ans++;
+    l = l->next;
+  }
+  return ans;
+}
+
+Stack *del_head(Stack *l) {
+  if (l == NULL)
+    return NULL;
+  else if (l->next == NULL) {
+    free(l);
+    l = NULL;
+    return NULL;
+  }
+  Stack *tmp = l->next;
+  free(l);
+  l = NULL;
+  return tmp;
+}

Homework/SC/head.h

@@ -0,0 +1,17 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+
+#define N 6
+
+typedef struct Stack {
+  double x;
+  struct Stack *next;
+} Stack;
+
+Stack get(Stack *l, int n);
+Stack *add_head(Stack *l, double x);
+void stack_print(Stack *l);
+int len(Stack *l);
+Stack *del_head(Stack *l);

Homework/SC/main.c

@@ -0,0 +1,61 @@
+#include "head.h"
+
+int main(int argc, char *argv[]) {
+  srand(time(0));
+  Stack *numbers = malloc(sizeof(Stack));
+  if (numbers == NULL)
+    exit(1);
+
+  char c;
+  char flag = 'f';
+
+  while ((c = getchar()) != EOF) {
+    if (c == '\n') {
+      break;
+    } else if (c == ' ') {
+      flag = 't';
+      continue;
+    }
+
+    switch (c) {
+    case '0' ... '9':
+      if (flag == 't') {
+        numbers = add_head(numbers, (double)(c - '0'));
+        flag = 'f';
+      } else {
+        double a = get(numbers, 0).x;
+        numbers = del_head(numbers);
+        a = a * 10 + c - '0';
+        numbers = add_head(numbers, a);
+      }
+      break;
+
+    case '+':
+    case '-':
+    case '*':
+    case '/':
+      if (len(numbers) < 2) {
+        printf("Invalid expression\n");
+        exit(2);
+      }
+
+      double a = get(numbers, 0).x;
+      numbers = del_head(numbers);
+      double b = get(numbers, 0).x;
+      numbers = del_head(numbers);
+
+      b = (c == '+') ? b + a : b;
+      b = (c == '-') ? b - a : b;
+      b = (c == '*') ? b * a : b;
+      b = (c == '/') ? b / a : b;
+
+      numbers = add_head(numbers, b);
+      break;
+    }
+  }
+
+  printf("result: %lF\n", get(numbers, 0).x);
+
+  free(numbers);
+  return 0;
+}