11-02-03.cpp

more efftive 代码

#include <iostream>
#include <cmath>
#include <cstring>
#include <algorithm>
using namespace std;

bool eq_nosign(int x, int y) { return abs(x) == abs(y); }

void lookup(int* first, int* last, size_t count, int val) {
  cout << "Searching for a sequence of "
       << count
       << " '" << val << "'"
       << (count != 1 ? "s: " : ":  ");
  int* result = search_n(first, last, count, val);
  if (result == last)
    cout << "Not found" << endl;
  else
    cout << "Index = " << result - first << endl;
}

void lookup_nosign(int* first, int* last, size_t count, int val) {
  cout << "Searching for a (sign-insensitive) sequence of "
       << count
       << " '" << val << "'"
       << (count != 1 ? "s: " : ":  ");
  int* result = search_n(first, last, count, val, eq_nosign);
  if (result == last)
    cout << "Not found" << endl;
  else
    cout << "Index = " << result - first << endl;
}

int main()
{
  const int N = 10;
  int A[N] = {1, 2, 1, 1, 3, -3, 1, 1, 1, 1};
  
  lookup(A, A+N, 1, 4);
  lookup(A, A+N, 0, 4);
  lookup(A, A+N, 1, 1);
  lookup(A, A+N, 2, 1);
  lookup(A, A+N, 3, 1);
  lookup(A, A+N, 4, 1);

  lookup(A, A+N, 1, 3);
  lookup(A, A+N, 2, 3);
  lookup_nosign(A, A+N, 1, 3);
  lookup_nosign(A, A+N, 2, 3);
}