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Albert Yang albertnetymk

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#include <iostream>
#include <cassert>
using namespace std;
static int a, b, c;
int new_sum(int sum, bool& terminated)

Find the max and min of sum of all permutations of [1..9] satisfying the following condition:

    == a[1] + a[2] + a[3]
    == a[3] + a[4] + a[5]
    == a[5] + a[6] + a[7]
    == a[7] + a[8]
    where sum = a[0] + a[1]

Racket lab

0 Background



DrRacket provides rudimentary features for Racket programming, you could experiment them by launch DrRacket directly. Some particularly interesting/useful ones are highlighted here:


Haskell lab

0. Warmup


Hoogle is the search engine for Haskell functions. It supports searching by function names and types.

For example, you plan to use parMap, but forget its type. You could just type parMap in Hoogle, and the search result would look like:

View box.hs
{-# LANGUAGE NamedFieldPuns #-}
import Data.List ((\\))
type Grid = [[Char]]
third_d :: Int -> Int -> Int
third_d x y = head $ [1..3] \\ [x,y]
data Op = L | R | U | D deriving (Show)
data State = State {

Def of project:

specific goal specific time period specific resource unique work arrangement temporary organization

The line is optimized towards routine work. When one new problem arises, one specific request is given to a project group through a project charter trying to solve this problem. After the problem is solved, the result is implemented in the line, and initiates new work routine in the line.

diffs between project manager and line manager:

View color_blender.c
#define MIN(a,b) (((a)<(b))?(a):(b))
typedef unsigned int uint;
typedef struct {
uint red:5;
uint green:6;
uint blue:5;
} f_pixel;
View hello.stp
global gc_major
global gc_minor
global gc_major_count
global gc_minor_count
global stat
global count_stat
probe process("/home/albert/github/otp/bin/x86_64-unknown-linux-gnu/beam.smp").mark("gc_major__start")
gc_major[user_string($arg1)] = gettimeofday_ms() - gc_major[user_string($arg1)]
View cache.c
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
// copied from
void insertion_sort (int *a, int n) {
int i, j, t;
for (i = 1; i < n; i++) {
t = a[i];
for (j = i; j > 0 && t < a[j - 1]; j--) {

How STM interacts with locks in kappa

I would firstly assume sync block has the same semantics of pthread_mutex_lock. When the execution outside of transactions reaches sync block, it would gain exclusive access to this critical region, and all other executions, either inside or outside transactions, are blocked if they try to enter the critical region.

When the execution inside of transactions reaches sync block, it would gain non-exclusive access to this critical region, which could be obtained by any other executions inside transactions, but executions outside transactions would be blocked.

In other words, the mutex lock inside the transactions becomes a reader lock, and mutex lock outside the transactions becomes a writer lock.

Software transactional memory