给定差值的组合

 

 思路：排序+二分

代码：

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

bool BinSerch(const vector<int>& arr, int start, int target)
{
    int left = start;
    int right = arr.size() - 1;
    while (left <= right) {
        int mid = left + (right - left) / 2;
        if (arr[mid] == target) {
            return true;
        } else if (arr[mid] < target) {
            left = mid + 1;
        } else if (arr[mid] > target) {
            right = mid - 1;
        }
    }
    return false;
}
// 待实现函数，在此函数中填入答题代码
int Proc(const vector<int>& arr, int diff)
{
    // 在此添加你的代码
    size_t arrLen = arr.size();
    vector<int> arrCur;
    arrCur.assign(arr.begin(), arr.end());
    int cnt = 0;
    sort(arrCur.begin(), arrCur.end());
    for (size_t i = 0; i < arrLen - 1; i++) {
        if ((diff > 0 && BinSerch(arrCur, i + 1, arrCur[i] + diff)) ||
        (diff < 0 && BinSerch(arrCur, i + 1, arrCur[i] - diff))) {
            cnt++;
        }
    }
    return cnt;
}

// 以下为考题输入输出框架，此部分代码不建议改动
int main()
{
    string line;
    getline(cin, line);
    int diff = stoi(line);

    getline(cin, line);
    int n = stoi(line);
    vector<int> arr(n);
    for (int i = 0; i < n; ++i) {
        cin >> arr[i];
    }
    cout << Proc(arr, diff) << endl;
    return 0;
}