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CS50 2022 - Lecture 0 - Scratch.pptx
- 3. 2/3 of CS50 students have never taken CS before
- 4. what ultimately matters in this course is not so much where you end up relative to your classmates but where you end up relative to yourself when you began
- 13. #include <stdio.h> int main(void) { printf("hello, worldn"); }
- 17. <!DOCTYPE html> <html lang="en"> <head> <title> hello, title </title> </head> <body> hello, body </body> </html> hello, title hello, body
- 20. CS50 Puzzle Day
- 23. CS50 Hackathon
- 27. CS50 Fair
- 32. computer science
- 34. problem solving
- 35. input → → output
- 36. representation
- 37. unary
- 38. base-1
- 39. binary digit
- 40. binary digit
- 41. binary digit
- 42. bitnary digi
- 43. 0
- 45. 1
- 48. base-2
- 49. base-10
- 50. decimal
- 51. 123
- 52. 123 1
- 53. 123 10 1
- 54. 123 100 10 1
- 55. 123 100 10 1 100 × 1
- 56. 123 100 10 1 100 × 1 10 × 2 +
- 57. 123 100 10 1 100 × 1 10 × 2 1 × 3 + +
- 58. 123 100 10 1 100 20 3 + +
- 59. 123
- 60. ### 100 10 1
- 61. ### 102 101 100
- 62. ### 22 21 20
- 63. ### 4 2 1
- 64. 000 4 2 1
- 65. 001 4 2 1
- 66. 010 4 2 1
- 67. 011 4 2 1
- 68. 100 4 2 1
- 69. 101 4 2 1
- 70. 110 4 2 1
- 71. 111 4 2 1
- 72. 000 4 2 1
- 73. 1000 4 2 1 8
- 74. 000 4 2 1
- 75. byte
- 76. 00000000
- 77. 11111111
- 78. A
- 79. 65
- 80. 01000001
- 81. ASCII
- 85. 72 73 33
- 86. H I 72 73 33
- 87. H I ! 72 73 33
- 93. Unicode
- 95. 4036991106
- 99. 🏻 🏼 🏽 🏾 🏿
- 104. RGB
- 106. 72 73 33
- 107. 72 73 33
- 115. input → → output
- 116. abstraction
- 117. input → → output
- 118. algorithm
- 124. n
- 125. n/2 n
- 126. n/2 n
- 127. n/2 n
- 128. n/2 n log2 n
- 129. pseudocode
- 130. 1 Pick up phone book 2 Open to middle of phone book 3 Look at page 4 If person is on page 5 Call person 6 Else if person is earlier in book 7 Open to middle of left half of book 8 Go back to line 3 9 Else if person is later in book 10 Open to middle of right half of book 11 Go back to line 3 12 Else 13 Quit
- 131. 1 Pick up phone book 2 Open to middle of phone book 3 Look at page 4 If person is on page 5 Call person 6 Else if person is earlier in book 7 Open to middle of left half of book 8 Go back to line 3 9 Else if person is later in book 10 Open to middle of right half of book 11 Go back to line 3 12 Else 13 Quit
- 132. 1 Pick up phone book 2 Open to middle of phone book 3 Look at page 4 If person is on page 5 Call person 6 Else if person is earlier in book 7 Open to middle of left half of book 8 Go back to line 3 9 Else if person is later in book 10 Open to middle of right half of book 11 Go back to line 3 12 Else 13 Quit
- 133. 1 Pick up phone book 2 Open to middle of phone book 3 Look at page 4 If person is on page 5 Call person 6 Else if person is earlier in book 7 Open to middle of left half of book 8 Go back to line 3 9 Else if person is later in book 10 Open to middle of right half of book 11 Go back to line 3 12 Else 13 Quit
- 134. 1 Pick up phone book 2 Open to middle of phone book 3 Look at page 4 If person is on page 5 Call person 6 Else if person is earlier in book 7 Open to middle of left half of book 8 Go back to line 3 9 Else if person is later in book 10 Open to middle of right half of book 11 Go back to line 3 12 Else 13 Quit
- 135. ● functions ○ arguments, return values ● conditionals ● Boolean expressions ● loops ● variables ● ...
- 137. #include <stdio.h> int main(void) { printf("hello, worldn"); }
- 148. input → → output algorithm
- 149. → → algorithm → output
- 150. → → → output
- 151. → →
- 153. input → → output algorithm
- 155. → → → output
- 156. → →
- 158. input → → output algorithm
- 160. → → → output
- 161. → →
- 162. →
- 163. →
- 164. → →
- 165. → → →
- 169. 1. Stand up and think of the number 1.
- 170. 1. Stand up and think of the number 1. 2. Pair off with someone standing, add their number to yours, and remember the sum.
- 171. 1. Stand up and think of the number 1. 2. Pair off with someone standing, add their number to yours, and remember the sum. 3. One of you should then sit down.
- 172. 1. Stand up and think of the number 1. 2. Pair off with someone standing, add their number to yours, and remember the sum. 3. One of you should then sit down. 4. If still standing, go back to step 2.
- 173. n/2 n log2 n
Editor's Notes
- http://hacks.mit.edu/Hacks/by_year/1991/fire_hydrant/
- Week 0
- cloud, then offboarding
- Week 1, debugging
- Week 2
- Week 2 Grace Hopper Mark II
- Week 3 https://www.cs.usfca.edu/~galles/visualization/ComparisonSort.html
- Week 4
- Week 4
- Week 5
- All that in C, then Python Week 6
- Week 6
- Week 7
- Week 7
- Week 8
- Week 9
- cloud, then offboarding
- study of information: how represent it, how process it?
- application of ideas from computer science to solving problems
- computers don't use fingers, they use 0s and 1s
- 0s and 1s
- 3 bulbs demo: but why these patterns? then 4 volunteers
- octet
- 255
- https://asciichart.com/
- https://asciichart.com/
- https://asciichart.com/
- https://asciichart.com/
- https://en.wikipedia.org/wiki/British_and_American_keyboards But how to represent other symbols?
- https://support.apple.com/guide/mac-help/enter-characters-with-accent-marks-on-mac-mh27474/12.0/mac/12.0
- https://support.apple.com/en-us/HT201586
- 4 billion, 36 million, 991 thousand, 1 hundred 6
- https://emojipedia.org/face-with-tears-of-joy/ Apple
- https://emojipedia.org/face-with-tears-of-joy/ Google
- https://emojipedia.org/loudly-crying-face/ Google #1 on Twitter in 2021, https://emojipedia.org/stats/
- Emoji Modifier Sequence https://emojipedia.org/emoji-modifier-sequence/ https://unicode.org/reports/tr51/proposed.html Fitzpatrick Scale
- https://emojipedia.org/couple-with-heart/ https://unicode.org/reports/tr51/proposed.html Zero Width Joiner (ZWJ) - "zwidge"
- https://emojipedia.org/couple-with-heart/ Zero Width Joiner (ZWJ) - "zwidge"
- https://emojipedia.org/couple-with-heart-woman-woman/ Zero Width Joiner (ZWJ) - "zwidge"
- https://emojipedia.org/couple-with-heart-man-man/ Zero Width Joiner (ZWJ) - "zwidge"
- Should be #484921ff, but brightened for projectors.
- This slide is actually #484921ff.
- https://youtu.be/p3q9MM__h-M
- note, duration, volume
- [Command byte] [Pitch byte] [Velocity/Volume byte]
- https://apps.apple.com/us/app/contacts/id1069512615#?platform=iphone
- https://scratch.mit.edu/projects/326949981/editor/
- Raining Men Andrew Berry, GM Cleveland Browns
- https://scratch.mit.edu/projects/326949981/editor/
- https://en.scratch-wiki.info/wiki/User_Interface#Code_Tab
- Block Palette
- Code Area
- Sprite Pane
- Stage
- function with argument and side effect
- function with argument and return value
- return value from one function as argument to other function
- https://emojipedia.org/cupcake/