69 lines
2.4 KiB
C
69 lines
2.4 KiB
C
/**
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* File: binary_search_insertion.c
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* Created Time: 2023-09-09
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* Author: Gonglja (glj0@outlook.com)
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*/
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#include "../utils/common.h"
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/* Binary search for insertion point (no duplicate elements) */
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int binarySearchInsertionSimple(int *nums, int numSize, int target) {
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int i = 0, j = numSize - 1; // Initialize double closed interval [0, n-1]
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while (i <= j) {
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int m = i + (j - i) / 2; // Calculate midpoint index m
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if (nums[m] < target) {
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i = m + 1; // Target is in interval [m+1, j]
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} else if (nums[m] > target) {
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j = m - 1; // Target is in interval [i, m-1]
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} else {
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return m; // Found target, return insertion point m
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}
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}
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// Did not find target, return insertion point i
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return i;
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}
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/* Binary search for insertion point (with duplicate elements) */
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int binarySearchInsertion(int *nums, int numSize, int target) {
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int i = 0, j = numSize - 1; // Initialize double closed interval [0, n-1]
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while (i <= j) {
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int m = i + (j - i) / 2; // Calculate midpoint index m
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if (nums[m] < target) {
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i = m + 1; // Target is in interval [m+1, j]
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} else if (nums[m] > target) {
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j = m - 1; // Target is in interval [i, m-1]
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} else {
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j = m - 1; // First element less than target is in interval [i, m-1]
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}
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}
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// Return insertion point i
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return i;
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}
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/* Driver Code */
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int main() {
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// Array without duplicate elements
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int nums1[] = {1, 3, 6, 8, 12, 15, 23, 26, 31, 35};
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printf("\nArray nums =");
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printArray(nums1, sizeof(nums1) / sizeof(nums1[0]));
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// Binary search for insertion point
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int targets1[] = {6, 9};
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for (int i = 0; i < sizeof(targets1) / sizeof(targets1[0]); i++) {
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int index = binarySearchInsertionSimple(nums1, sizeof(nums1) / sizeof(nums1[0]), targets1[i]);
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printf("Index of insertion point for element %d = %d\n", targets1[i], index);
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}
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// Array with duplicate elements
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int nums2[] = {1, 3, 6, 6, 6, 6, 6, 10, 12, 15};
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printf("\nArray nums =");
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printArray(nums2, sizeof(nums2) / sizeof(nums2[0]));
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// Binary search for insertion point
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int targets2[] = {2, 6, 20};
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for (int i = 0; i < sizeof(targets2) / sizeof(int); i++) {
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int index = binarySearchInsertion(nums2, sizeof(nums2) / sizeof(nums2[0]), targets2[i]);
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printf("Index of insertion point for element %d = %d\n", targets2[i], index);
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}
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return 0;
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}
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