第六届蓝桥杯2015-省赛-C语言大学B组 个人题解

题目连接：http://course.baidu.com/view/2d86a6c1960590c69fc37622.html

1，奖券数目52488

#include <iostream>
using namespace std;
bool isOK(int a)
{
	while(a)
	{
		if(a%10==4) return false;
		a /= 10;
	}
	return true;
}
int main()
{
	int ans = 0;
	for(int i=10000; i<=99999; i++)
	{
		if(isOK(i))
		{
			ans++;
		}
	}
	cout << ans << endl;
	return 0;
}

2，星系炸弹2017-08-05

#include <iostream>
using namespace std;
bool jwd(int y, int m, int d)
{
	if(m==4 || m==6 || m==9 || m==11)
	{
		return d > 30;
	}else if(m==2)
	{
		if((y%4==0 && y%100!=0) || (y%400==0))
		{
			return d > 29;
		}else{
			return d > 28;
		}
	}else{
		return d > 31;
	}
}
int main()
{
	int y, m, d, ct = 1000;
	y = 2014;
	m = 11;
	d = 9;
	while(ct--)
	{
		d++;
		if(jwd(y, m, d))
		{
			d = 1;
			m++;
		}
		if(m>12)
		{
			m = 1;
			y++;
		}
	}
	cout << y << "-" << m << "-" << d << endl;
	return 0;
}

3，三羊献瑞1085

暴力枚举做的

4，格子中输出(width-2-strlen(buf))/2,"",buf,width-2-(width-2-strlen(buf))/2-strlen(buf),""

5，九数组分数{t=x[k]; x[k]=x[i]; x[i]=t;}

6，加法变乘法16

#include <iostream>
using namespace std;
int main()
{
	int a, b, sum = 1225;
	for(a=1; a<=49; a++)
	{
		for(b=a+2; b<=49; b++)
		{
			int k = sum - 2*a - 1 - 2*b - 1 + a*a + a + b*b + b;
			if(k == 2015)
			{
				cout << a << endl;
			}
		}
	}
	return 0;
}

7，牌型种数3598180

#include <iostream>
using namespace std;
int dfs(int pai, int ct)
{
	if(pai == 13)
	{
		return ct <= 4;
	}
	int res = 0;
	res += dfs(pai+1, ct);
	if(ct >= 1)
	res += dfs(pai+1, ct-1);
	if(ct >= 2)
	res += dfs(pai+1, ct-2);
	if(ct >= 3)
	res += dfs(pai+1, ct-3);
	if(ct >= 4)
	res += dfs(pai+1, ct-4);
	return res;
}
int main()
{
	cout << dfs(1, 13) << endl;
	return 0;
}

8,移动距离

#include <iostream>
using namespace std;
int main()
{
	int w, n, m;
	int x1, y1, x2, y2;
	cin >> w >> m >> n;
	x1 = (m + w - 1) / w;
	if(x1%2==1)
	{
		y1 = m - (x1 - 1) * w;

	}else{
		y1 = w - (m - (x1 - 1) * w) + 1;
	}
	x2 = (n + w - 1) / w;
	if(x2%2==1)
	{
		y2 = n - (x2 - 1) * w;

	}else{
		y2 = w - (n - (x2 - 1) * w) + 1;
	}
	int ans = 0;
	if(x1 > x2)
	{
		ans += x1 - x2;
	}else{
		ans += x2 - x1;
	}
	if(y1 > y2)
	{
		ans += y1 - y2;
	}else{
		ans += y2 - y1;
	}
	cout << ans << endl;
	return 0;
}

9，垒骰子

#include <iostream>
#include <cstring>
using namespace std;
const int MOD = 1000000007;
bool ok[7][7];
__int64 dp[110000][7];
__int64 dfs(int n,int pre)
{
	if(n==0)
	{
		return dp[n][pre] = 1;
	}
	if(dp[n][pre]!=-1) return dp[n][pre];
	__int64 res = 0;
	for(int i=1; i<=6; i++)
	{
		if(ok[pre][i])
		res += dfs(n-1, i)*4;
	}
	return dp[n][pre] = res%MOD;
}
int main()
{
	int n, m, a, b;
	cin >> n >> m;
	memset(dp, -1, sizeof (dp));
	for(int i=0; i<=6; i++)
	{
		for(int j=0; j<=6; j++)
		{
			ok[i][j] = true;
		}
	}
	while(m--)
	{
		cin >> a >> b;
		ok[a][b] = ok[b][a] = false;
	}
	cout << dfs(n, 0) << endl;
	return 0;
}

这个只能过60%，数学不会没办法，看大神的题解好像是要矩阵快速乘法

10，生命之树

#include <iostream>
#include <stdio.h>
#include <vector>
#include <cstring>
using namespace std;
vector<int>G[100010];
int val[100010];
bool use[100010];
__int64 ans;
__int64 dfs(int xb)
{
	use[xb] = true;
	__int64 res = val[xb];
	for(int i=0; i<G[xb].size(); i++)
	{
		 int k = G[xb][i];
		 if(!use[k])
		 {
		 	int b = dfs(k);
		 	if(b>0)
		 	res += b;
		 }
	}
	if(ans < res)
	{
		ans = res;
	}
	return res;
}
int main()
{
	int n, i, a, b;
	scanf("%d", &n);
	for(i=1; i<=n; i++)
	{
		scanf("%d", &val[i]);
		G[i].clear();
	}
	for(i=1; i<n; i++)
	{
		scanf("%d %d",&a, &b);
		G[a].push_back(b);
		G[b].push_back(a);
	}
	memset(use, 0, sizeof (use));
	ans = val[1];
	dfs(1);
	cout << ans << endl;
	return 0;
}

蓝桥杯已经算是告一段落咯，数学题目什么都还不会，得要加油学习了！