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CS50 Lecture2
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- 8. 01111111 01000101 0100110001000110 00000010 00000001 00000001 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000010 00000000 00111110 00000000 00000001 00000000 00000000 00000000 10110000 00000101 01000000 00000000 00000000 00000000 00000000 00000000 01000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 11010000 00010011 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 01000000 00000000 00111000 00000000 00001001 00000000 01000000 00000000 00100100 00000000 00100001 00000000 00000110 00000000 00000000 00000000 00000101 00000000 00000000 00000000 01000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 01000000 00000000 01000000 00000000 00000000 00000000 00000000 00000000 01000000 00000000 01000000 00000000 00000000 00000000 00000000 00000000 11111000 00000001 00000000 00000000 00000000 00000000 00000000 00000000 11111000 00000001 00000000 00000000 00000000 00000000 00000000 00000000 00001000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000011 00000000 00000000 00000000 00000100 00000000 00000000 00000000 00111000 00000010 00000000 00000000 00000000 00000000 00000000 00000000 ...
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- 10. clang -o hellohello.c ./hello
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- 13. #include <cs50.h> #include <stdio.h> intmain(void) { string name = get_string("Name: "); printf("hello, %sn", name); }
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- 16. clang -o hellohello.c -lcs50 ./hello
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- 21. #include <cs50.h> #include <stdio.h> intmain(void) { string name = get_string("Name: "); printf("hello, %sn", name); }
- 22. #include <cs50.h> #include <stdio.h> intmain(void) { string name = get_string("Name: "); printf("hello, %sn", name); }
- 23. string get_string(string prompt); #include<stdio.h> int main(void) { string name = get_string("Name: "); printf("hello, %sn", name); }
- 24. string get_string(string prompt); #include<stdio.h> int main(void) { string name = get_string("Name: "); printf("hello, %sn", name); }
- 25. string get_string(string prompt); intprintf(const char *format, ...); int main(void) { string name = get_string("Name: "); printf("hello, %sn", name); }
- 26. ... string get_string(string prompt); intprintf(const char *format, ...); ... int main(void) { string name = get_string("Name: "); printf("hello, %sn", name); }
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- 28. ... string get_string(string prompt); intprintf(const char *format, ...); ... int main(void) { string name = get_string("Name: "); printf("hello, %sn", name); }
- 29. ... main: # @main .cfi_startproc #BB#0: pushq %rbp .Ltmp0: .cfi_def_cfa_offset 16 .Ltmp1: .cfi_offset %rbp, -16 movq %rsp, %rbp .Ltmp2: .cfi_def_cfa_register %rbp subq $16, %rsp xorl %eax, %eax movl %eax, %edi movabsq $.L.str, %rsi movb $0, %al callq get_string movabsq $.L.str.1, %rdi movq %rax, -8(%rbp) movq -8(%rbp), %rsi movb $0, %al callq printf ...
- 30. ... main: # @main .cfi_startproc #BB#0: pushq %rbp .Ltmp0: .cfi_def_cfa_offset 16 .Ltmp1: .cfi_offset %rbp, -16 movq %rsp, %rbp .Ltmp2: .cfi_def_cfa_register %rbp subq $16, %rsp xorl %eax, %eax movl %eax, %edi movabsq $.L.str, %rsi movb $0, %al callq get_string movabsq $.L.str.1, %rdi movq %rax, -8(%rbp) movq -8(%rbp), %rsi movb $0, %al callq printf ...
- 31. ... main: # @main .cfi_startproc #BB#0: pushq %rbp .Ltmp0: .cfi_def_cfa_offset 16 .Ltmp1: .cfi_offset %rbp, -16 movq %rsp, %rbp .Ltmp2: .cfi_def_cfa_register %rbp subq $16, %rsp xorl %eax, %eax movl %eax, %edi movabsq $.L.str, %rsi movb $0, %al callq get_string movabsq $.L.str.1, %rdi movq %rax, -8(%rbp) movq -8(%rbp), %rsi movb $0, %al callq printf ...
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- 34. ... main: # @main .cfi_startproc #BB#0: pushq %rbp .Ltmp0: .cfi_def_cfa_offset 16 .Ltmp1: .cfi_offset %rbp, -16 movq %rsp, %rbp .Ltmp2: .cfi_def_cfa_register %rbp subq $16, %rsp xorl %eax, %eax movl %eax, %edi movabsq $.L.str, %rsi movb $0, %al callq get_string movabsq $.L.str.1, %rdi movq %rax, -8(%rbp) movq -8(%rbp), %rsi movb $0, %al callq printf ...
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- 59. input → →output
- 60. plaintext → →ciphertext
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- 66. plaintext → →ciphertext
- 67. plaintext → →ciphertext key →
- 68. plaintext → →ciphertext 1 →
- 69. I L OV E Y O U
- 70. 73 L OV E Y O U
- 71. 73 76 OV E Y O U
- 72. 73 76 79V E Y O U
- 73. 73 76 7986 E Y O U
- 74. 73 76 7986 69 Y O U
- 75. 73 76 7986 69 89 O U
- 76. 73 76 7986 69 89 79 U
- 77. 73 76 7986 69 89 79 85
- 78. 74 76 7986 69 89 79 85
- 79. 74 77 7986 69 89 79 85
- 80. 74 77 8086 69 89 79 85
- 81. 74 77 8087 69 89 79 85
- 82. 74 77 8087 70 89 79 85
- 83. 74 77 8087 70 90 79 85
- 84. 74 77 8087 70 90 80 85
- 85. 74 77 8087 70 90 80 86
- 86. J 77 8087 70 90 80 86
- 87. J M 8087 70 90 80 86
- 88. J M P87 70 90 80 86
- 89. J M PW 70 90 80 86
- 90. J M PW F 90 80 86
- 91. J M PW F Z 80 86
- 92. J M PW F Z P 86
- 93. J M PW F Z P V
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- 96. #include <stdio.h> int main(intargc, string argv[]) { ... }
- 97. #include <stdio.h> int main(intargc, string argv[]) { ... }
- 98. #include <stdio.h> int main(intargc, string argv[]) { ... }
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- 104. repeat until noswaps for i from 0 to n-2 if i'th and i+1'th elements out of order swap them
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- 106. for i from0 to n-1 find smallest element between i'th and n-1'th swap smallest with i'th element
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- 108. (n – 1)+ (n – 2)
- 109. (n – 1)+ (n – 2) + ... + 1
- 110. (n – 1)+ (n – 2) + ... + 1 n(n – 1)/2
- 111. (n – 1)+ (n – 2) + ... + 1 n(n – 1)/2 (n2 – n)/2
- 112. (n – 1)+ (n – 2) + ... + 1 n(n – 1)/2 (n2 – n)/2 n2 /2 – n/2
- 113. (n – 1)+ (n – 2) + ... + 1 n(n – 1)/2 (n2 – n)/2 n2 /2 – n/2 O(n2 )
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- 115. n2 /2 – n/2 1,000,0002 /2– 1,000,000/2
- 116. n2 /2 – n/2 1,000,0002 /2– 1,000,000/2 500,000,000,000 – 500,000
- 117. n2 /2 – n/2 1,000,0002 /2– 1,000,000/2 500,000,000,000 – 500,000 499,999,500,000
- 118. n2 /2 – n/2 1,000,0002 /2– 1,000,000/2 500,000,000,000 – 500,000 499,999,500,000 O(n2 )
- 119. O(n2 ) O(n log n) O(n) O(logn) O(1)
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- 122. Ω(n2 ) Ω(n log n) Ω(n) Ω(logn) Ω(1)
- 123. Θ(n2 ) Θ(n log n) Θ(n) Θ(logn) Θ(1)
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- 125. on input ofn elements if n < 2 return else sort left half of elements sort right half of elements merge sorted halves
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