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[์ •๋ณด์ฒ˜๋ฆฌ๊ธฐ์‚ฌ] ์‹ค๊ธฐ ํ”„๋กœ๊ทธ๋ž˜๋ฐ์–ธ์–ด 3๋ฌธ์ œ (16)

by Sun A 2024. 10. 2.

1๏ธโƒฃ [SQL]

2020.2

๋‹ค์Œ ์ฃผ์–ด์ง„ student ํ…Œ์ด๋ธ”์˜ name ์†์„ฑ์— idx_name๋ฅผ ์ธ๋ฑ์Šค ๋ช…์œผ๋กœ ํ•˜๋Š” ์ธ๋ฑ์Šค๋ฅผ ์ƒ์„ฑํ•˜๋Š” SQL๋ฌธ์„ ์ž‘์„ฑํ•˜์‹œ์˜ค.

id name grade
1111 ํ™๊ธธ๋™ 1
2222 ์ž„๊บฝ์ • 2
3333 ์œ ๊ด€์ˆœ 3
4444 ์•ˆ์ค‘๊ทผ 3
5555 ํ™๋ฒ”๋„ 4
CREATE INDEX idx_name ON student(name);

 

2๏ธโƒฃ [JAVA]

2022.3ํšŒ

๋‹ค์Œ ์ž๋ฐ” ์ฝ”๋“œ์— ๋Œ€ํ•œ ์ถœ๋ ฅ ๊ฐ’์„ ์ž‘์„ฑํ•˜์‹œ์˜ค.


  
public class Exam {
public static void main(String[] args){
int a = 0;
for(int i=1; i<999; i++){
if(i%3==0 && i%2!=0)
a = i;
}
System.out.print(a);
}
993

๋ฐ˜๋ณต๋ฌธ์˜ i๊ฐ€ 999๋ผ๋Š” ํฐ ์ˆซ์ž๋ณด๋‹ค ์ ์„๋•Œ๊นŒ์ง€ ๋ฐ˜๋ณตํ•˜๊ธฐ ๋•Œ๋ฌธ์— if ์กฐ๊ฑด๋ฌธ์˜ ๊ทœ์น™์„ ๋จผ์ € ์‚ดํŽด๋ณธ๋‹ค.

i๋ฅผ 3์œผ๋กœ ๋‚˜๋ˆด์„ ๋•Œ ๋‚˜๋ˆ„์–ด ๋–จ์–ด์ง€๋ฉด์„œ 2๋กœ ๋‚˜๋ˆˆ ๋‚˜๋จธ์ง€๊ฐ€ 0์ด ์•„๋‹ˆ๋ผ๋ฉด ํ™€์ˆ˜์ด๋ฉด์„œ 3์˜ ๋ฐฐ์ˆ˜ ์ค‘์— ๊ฐ€์žฅ ํฐ ์ˆ˜๋ฅผ ๊ตฌํ•˜๋Š” ์‹์ด๋‹ค.

a์˜ ๊ฐ’์€ ๋‚˜์˜ค๋Š” ๊ฐ’๋“ค์˜ ํ•ฉ์ด ์•„๋‹Œ, ๊ฐ€์žฅ ํฐ ์ˆ˜๋กœ ๋ฐ”๋€Œ๋Š” ๊ฐ’์ด๊ธฐ ๋•Œ๋ฌธ์— 999๋ณด๋‹ค ์ž‘์œผ๋ฉด์„œ 3์˜ ๋ฐฐ์ˆ˜์ธ ํ™€์ˆ˜๋Š” 993์ด๋‹ค.

 

3๏ธโƒฃ [JAVA]

2022.2

๋‹ค์Œ ์ž๋ฐ”์ฝ”๋“œ์—์„œ ์•Œ๋งž๋Š” ์ถœ๋ ฅ๊ฐ’์„ ์ž‘์„ฑํ•˜์‹œ์˜ค.


  
public class Conv{
public Conv(int a) {
this.a = a;
}
int func() {
int b =1;
for (int i=1; i<a; i++){
b = a * i + b
}
return a +b;
}
int a;
}
public static void main(String[] args){
Conv obj = new Conv(3);
obj.a=5;
int b = obj.func();
system.out.print(obj.a + b);
}
61

main ๋จผ์ € ์‚ดํŽด๋ณด๋ฉด obj ์— Conv(3)์„ ์„ ์–ธํ–ˆ๋‹ค.

Conv์˜ class๋กœ ๊ฐ€์„œ this.a = a๋กœ ์„ ์–ธํ–ˆ๊ธฐ์— a์˜ ๊ฐ’์€ 3์œผ๋กœ ์ •์˜๋˜์—ˆ๋‹ค.

obj.a = 5;

๋กœ obj.a๋Š” 5๋ผ๋Š” ๊ฐ’์„ ๊ฐ€์ง„๋‹ค.

obj.func()๋ฅผ ๊ณ„์‚ฐํ•ด๋ณด๋ฉด, ํ˜„์žฌ a ๊ฐ’์— 5๋ผ๊ณ  ์ •์˜๋œ ์ƒํƒœ์ด๊ธฐ ๋•Œ๋ฌธ์— 

b i a * i + b
1 1 5*1+1 = 6
6 2 5*2+6 = 16
16 3 5*3+16 = 31
31 4 5*4+31 = 51

return a + b = 5 + 51 = 56

56์ด b ๊ฐ’์ด ๋œ๋‹ค,

print๊ฐ’ (obj.a + b)๋ฅผ ๊ณ„์‚ฐํ•˜๋ฉด 5 + 56 = 61