some exercises added here that aren't done, will do later

1 files changed, 47 insertions, 0 deletions

diff --git a/9p31.cpp b/9p31.cpp
new file mode 100644
index 0000000..38db051
--- /dev/null
+++ b/9p31.cpp
@@ -0,0 +1,47 @@
+#include <iostream>
+#include <list>
+#include <forward_list>
+
+/*
+ *
+ * 9.31
+ *
+ * A lot of comments here but i had to do it to clear it up in my head
+ */
+
+int main () {
+
+	std::list<int> vi = {0,1,2,3,4,5,6,7,8,9};
+	auto iter = vi.begin(); // get begin
+	while (iter != vi.end()) { // when begin is not at the end
+		if (*iter % 2 == 1) { // when it's odd
+			iter = vi.insert(iter, *iter); // insert whatever is at *iter before iter and return iterator where the new value was inserted
+			
+			++iter; // advance past what was inserted
+			++iter; // advance past the element we checked for odd/even(ness)
+		} else // when even
+			iter = vi.erase(iter); // remove the even value, return iterator to element after the erased element
+	}
+
+	std::forward_list<int> fli = {0,1,2,3,4,5,6,7,8,9};
+	auto beg = fli.begin(); // get begin
+	auto bbeg = fli.before_begin(); // get before begin
+	while (beg != fli.end()) { // while beg is not at the end
+		if (*beg % 2 == 1) { // when odd
+			bbeg = fli.insert_after(bbeg, *beg); // insert *beg after bbeg, returns iterator to inserted element
+			++beg; // advance beg to next element to be checked
+			++bbeg; // advance bbeg to follow beg one value behind
+		} else // when it's even
+			beg = fli.erase_after(bbeg); // erase element after bbeg (the one at beg). Returns iterator to element after erased one (aka next one to be checked)
+	}
+
+	for(auto &a : vi) {
+		std::cout << a << std::endl;
+	}
+	
+	for(auto &a : fli) {
+		std::cout << a << std::endl;
+	}
+	
+	return 0;
+}