STL 学习代码~

#include<stdio.h>
#include<numeric>
#include<iostream>
#include<functional>
#include<algorithm>
#include<vector>
using namespace std;
#define LL long long
#define nmax 20
int num[nmax];
struct node {
    int x;
};
struct Add {
    int operator()(int n, node &M) const {
        return n + M.x;
    }
};
node Node[nmax];
vector<int> first, second, third, four;
int op_increase(int a) {
    return ++a;
}
int op_sum(int a, int b) {
    return a + b;
}
int main() {
#ifndef ONLINE_JUDGE
    freopen("data.in", "r", stdin);
#endif
    int i, k;
    for (i = 0; i < nmax; i++) {
        num[i] = i + 1;
        Node[i].x = i + 1;
        first.push_back((i + 1) * 10);
    }
    second.resize(first.size());
    transform(first.begin(), first.end(), second.begin(), op_increase);
    for (i = 0; i < nmax; i++) {
        cout << first[i] << " ";
    }
    cout << endl;
    for (i = 0; i < nmax; i++) {
        cout << second[i] << " ";
    }
    third.resize(first.size());
    transform(first.begin(), first.end(), second.begin(), third.begin(),
            op_sum);
    for (i = 0; i < nmax; i++) {
        cout << first[i] << " ";
    }
    cout << endl;
    for (i = 0; i < nmax; i++) {
        cout << second[i] << " ";
    }
    cout << endl;
    for (i = 0; i < nmax; i++) {
        cout << third[i] << " ";
    }
    cout << endl;
    four.resize(first.size());
    transform(first.begin(), first.end(), four.begin(),
            bind2nd(modulus<int>(), 6));
    for (i = 0; i < nmax; i++) {
        cout << four[i] << " ";
    }
    cout << endl << accumulate(four.begin(), four.end(), 0) << endl;

    printf("%d %I64d\n", accumulate(num, num + nmax,0),
            accumulate(num, num + nmax,1LL,multiplies<LL>()));
    printf("%d\n", accumulate(Node, Node + nmax, 0,Add()));
    copy(num, num + nmax,ostream_iterator<int>(cout, " "));
    cout << endl;
    vector<int> vec(num, num + nmax);
    k = count_if(vec.begin(), vec.end(), bind1st(greater<int>(), 5));
    printf("%d\n", k);
    k = count_if(vec.begin(), vec.end(), bind2nd(greater<int>(), 5));
    printf("%d\n", k);
    transform(num, num + nmax,num,bind2nd(modulus<int>(), 5));
    for (i = 0; i < nmax; i++) {
        printf("%d ", num[i]);
    }
    printf("\n%d\n", accumulate(num, num + nmax,0));
    return 0;
}