67 lines
1.8 KiB
C++
67 lines
1.8 KiB
C++
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/**
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* File: binary_search_edge.cpp
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* Created Time: 2023-08-04
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* Author: krahets (krahets@163.com)
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*/
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#include "../utils/common.hpp"
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/* <20><><EFBFBD>ֲ<EFBFBD><D6B2>Ҳ<EFBFBD><D2B2><EFBFBD><EFBFBD>㣨<EFBFBD><E3A3A8><EFBFBD><EFBFBD><EFBFBD>ظ<EFBFBD>Ԫ<EFBFBD>أ<EFBFBD> */
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int binarySearchInsertion(const vector<int> &nums, int target) {
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int i = 0, j = nums.size() - 1; // <20><>ʼ<EFBFBD><CABC>˫<EFBFBD><CBAB><EFBFBD><EFBFBD><EFBFBD><EFBFBD> [0, n-1]
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while (i <= j) {
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int m = i + (j - i) / 2; // <20><><EFBFBD><EFBFBD><EFBFBD>е<EFBFBD><D0B5><EFBFBD><EFBFBD><EFBFBD> m
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if (nums[m] < target) {
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i = m + 1; // target <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD> [m+1, j] <20><>
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} else {
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j = m - 1; // <20><EFBFBD>С<EFBFBD><D0A1> target <20><>Ԫ<EFBFBD><D4AA><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> [i, m-1] <20><>
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}
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}
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// <20><><EFBFBD>ز<EFBFBD><D8B2><EFBFBD><EFBFBD><EFBFBD> i
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return i;
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}
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/* <20><><EFBFBD>ֲ<EFBFBD><D6B2><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><D2BB> target */
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int binarySearchLeftEdge(vector<int> &nums, int target) {
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// <20>ȼ<EFBFBD><C8BC>ڲ<EFBFBD><DAB2><EFBFBD> target <20>IJ<EFBFBD><C4B2><EFBFBD><EFBFBD><EFBFBD>
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int i = binarySearchInsertion(nums, target);
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// δ<>ҵ<EFBFBD> target <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD> -1
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if (i == nums.size() || nums[i] != target) {
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return -1;
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}
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// <20>ҵ<EFBFBD> target <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> i
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return i;
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}
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/* <20><><EFBFBD>ֲ<EFBFBD><D6B2><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><D2BB> target */
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int binarySearchRightEdge(vector<int> &nums, int target) {
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// ת<><D7AA>Ϊ<EFBFBD><CEAA><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><D2BB> target + 1
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int i = binarySearchInsertion(nums, target + 1);
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// j ָ<><D6B8><EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><D2BB> target <20><>i ָ<><D6B8><EFBFBD><EFBFBD><D7B8><EFBFBD><EFBFBD><EFBFBD> target <20><>Ԫ<EFBFBD><D4AA>
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int j = i - 1;
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// δ<>ҵ<EFBFBD> target <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD> -1
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if (j == -1 || nums[j] != target) {
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return -1;
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}
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// <20>ҵ<EFBFBD> target <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> j
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return j;
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}
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/* Driver Code */
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int main() {
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// <20><><EFBFBD><EFBFBD><EFBFBD>ظ<EFBFBD>Ԫ<EFBFBD>ص<EFBFBD><D8B5><EFBFBD><EFBFBD><EFBFBD>
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vector<int> nums = {1, 3, 6, 6, 6, 6, 6, 10, 12, 15};
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cout << "\n<EFBFBD><EFBFBD><EFBFBD><EFBFBD> nums = ";
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printVector(nums);
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// <20><><EFBFBD>ֲ<EFBFBD><D6B2><EFBFBD><EFBFBD><EFBFBD><EFBFBD>߽<EFBFBD><DFBD><EFBFBD><EFBFBD>ұ߽<D2B1>
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for (int target : {6, 7}) {
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int index = binarySearchLeftEdge(nums, target);
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cout << "<EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD>Ԫ<EFBFBD><EFBFBD> " << target << " <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ϊ " << index << endl;
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index = binarySearchRightEdge(nums, target);
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cout << "<EFBFBD><EFBFBD><EFBFBD><EFBFBD>һ<EFBFBD><EFBFBD>Ԫ<EFBFBD><EFBFBD> " << target << " <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ϊ " << index << endl;
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}
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return 0;
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}
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