Algorithm Complexity

In the early computer course, the only thing we care is the final performance of our coding, but we should also care about the time and spaces required to preform the operation since we have limited hardware and humans dont live forever. To minimize the time/space used, we should first find out the order of our function which can be constant, logarithmic, linear, quadratic, cubic, exponential or even worse , and if we have different Algorithms which done the same task , the best-order one is prefered.