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algorithm [2015/12/27 12:15] – [이진 탐색 (Binary Search)] ledyxalgorithm [2021/02/07 03:15] (current) – external edit 127.0.0.1
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-= Algorithm = +~~REDIRECT>algorithm:algorithm~~
- +
-{{tag>Algorithm}} +
- +
-= 마방진 (Magic Square) = +
-  * 홀수만 처리 가능! +
-<sxh java ; title:Language : Java> +
-int size = 5; +
- +
-int[][] arr = new int[size][size]; +
-  +
-int middle = size/2; +
- +
-int i=0, j=middle; +
-for(int num=1 ; num<=size*size ; num++) { +
- arr[i][j] = num; +
-  +
- //행 감소 +
- i--; +
- if(i < 0) +
- i = size-1; +
-  +
- //열 증가 +
- j = (++j)%size; +
- //아래 표현과 같다. +
- /*j++; +
- if(j >= size) +
- j = 0;*/ +
- +
- //배수이면 행은 1 증가, 열은 그대로 +
- if(num%size == 0) { +
- i = (i+2)%size; +
- j--; +
- if(j < 0) +
- j = size-1; +
- } +
-} +
-</sxh> +
- +
-= 합병 정렬 (Merge Sort) = +
-[[Merge Sort]] +
- +
-= 이진 탐색 (Binary Search) = +
-  * A ＜ X ≤ B 조건을 검색. +
-<sxh java> +
- // A < X <= B +
- public static int binarySearch(int[] arr, int target) { +
- if(arr[arr.length - 1] < target) +
- return arr.length - 1; +
-  +
- int left = 0; +
- int right = arr.length; +
- +
- int result = -1; +
-  +
- while (left <= right) { +
- int mid = (left + right) / 2; +
- +
- if (mid > 0) { +
-  +
- int limit = arr[mid]; +
-  +
- if (arr[mid - 1] <= target && target <= limit) { +
-  +
- //A < X <= B +
- if(arr[mid] == target) { +
-  +
- if(mid >= arr.length - 1) { +
- result = mid; +
- } +
- else { +
- result = mid + 1; +
- } +
- } +
- else +
- result = mid; +
-  +
-  +
- break; +
- } +
- else if(target > limit) +
- left = mid + 1; +
- else if(target < limit) +
- right = mid - 1; +
-  +
- } +
- else { +
- //첫번째 index보다 작은 값일 때 +
- result = 0; +
- break; +
- } +
- } +
-  +
- return result; +
- } +
-</sxh>+
algorithm.1451218523.txt.gz · Last modified: 2021/02/07 03:15 (external edit)