2014.12.15（14/42）

A - Past ABCs

#include <iostream>
#include <string>
using namespace std;

int main()
{
	string s;
	cin >> s;
	if (s[0] != 'A' || s[1] != 'B' || s[2] != 'C') {
		cout << "No" << endl;
		return 0;
	}
	int n = (s[3] - '0') * 100 + (s[4] - '0') * 10 + (s[5] - '0');
	if (n != 316 && n > 0 && n <= 349)cout << "Yes" << endl;
	else cout << "No" << endl;
	


	return 0;
}

B - The bottom of the ninth

#include <iostream>
#include <string>
using namespace std;

int main()
{
	int sum1 = 0;
	int sum2 = 0;
	for (int i = 0; i < 9; i++) {
		int x;
		cin >> x;
		sum1 += x;
	}
	for (int i = 0; i < 8; i++) {
		int x;
		cin >> x;
		sum2 += x;
	}
	int sum = sum1+1;
	cout << sum-sum2 << endl;

	return 0;
}

C - Dentist Aoki

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

int main()
{
	int n, q;
	cin >> n >> q;
	int sum = n;
	bool vec[1005];
	for (int i = 1; i < n + 2; i++)vec[i] = true;
	for (int i = 0; i < q; i++) {
		int x;
		cin >> x;
		if (vec[x] == true) {
			vec[x] = false;
			sum--;
		}
		else {
			vec[x] = true;
			sum++;
		}
	}
	cout << sum << endl;

	return 0;
}

D - Spot the Difference

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

int main()
{
	int n;
	cin >> n;
	char a[105][105];
	char b[105][105];
	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= n; j++) {
			cin >> a[i][j];
		}
	}
	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= n; j++) {
			cin >> b[i][j];
		}
	}


	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= n; j++) {
			if (a[i][j] != b[i][j]) {
				cout << i << " " << j << endl;
				return 0;
			}
		}
	}

	return 0;
}

E - Sort

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

int main() 
{
    int n;
    cin >> n;

    vector<int>a(n + 1);
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
    }
    
    vector<pair<int, int>>operation;
    for (int i = 1; i <= n; i++) {
        while (a[i] != i) {
            int correct_pos = a[i];
            swap(a[i], a[correct_pos]);
            operation.push_back({ i,correct_pos });
        }
    }
    cout << operation.size() << endl;
    for (const auto& op : operation) {
        cout << op.first << " " << op.second << endl;
    }


    return 0;
}

注意：

我一开始一直在想怎么排序，然后使用了选择排序，于是超时了。后面发现，原来直接每个下标就是对应排序后的元素，是我观察不够仔细。

F - Merge the balls

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

int main()
{
	int n;
	cin >> n;

	int count = n;
	stack<int>stk;
	vector<int>vec(n);

	for (int i = 0; i < n; i++) {
		cin >> vec[i];
	}
	for (int i = 0; i < n; i++) {
		while (!stk.empty() && vec[i]==stk.top() ){
			stk.pop();
			vec[i]++;
		}
		stk.push(vec[i]);
	}
	cout << stk.size() << endl;

	return 0;
}

G - New Friends

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

const int N = 2e5 + 5;
vector<int>e[N];
int vis[N];

int main()
{
	int n, m;
	cin >> n >> m;
	int u, v;
	for (int i = 0; i < m; i++) {
		cin >> u >> v;
		e[u].push_back(v);
		e[v].push_back(u);
	}
	long long ans = 0;
	for (int i = 1; i <= n; i++) {
		if (vis[i])continue;
		queue<int>que;
		que.push(i);
		vis[i] = 1;
		long long sumn = 1, summ = e[i].size();
		while (!que.empty()) {
			int t = que.front();
			que.pop();
			for (int w : e[t]) {
				if (!vis[w]) {
					vis[w] = 1;
					que.push(w);
					sumn++;
					summ += e[w].size();
				}
			}
		}
		ans += sumn * (sumn - 1) - summ;
	}
	cout << ans / 2 << endl;

	return 0;
}

同类型题，横向对比：

（1）12.8（12）的F题

（2）11.24（46）的F和G题