蓝桥月赛总结

2.蓝桥字符

求子序列出现次数，动态规划思想，

#include<bits/stdc++.h>
#define int long long
using namespace std;
string s; 
signed main()
{
	cin>>s;
	int sum1=0,sum2=0,sum3=0;
	for(char ch:s)
	{
		if(ch=='l')
		{
			sum1++;
		}
		else if(ch=='a')
		{
			sum2+=sum1;
		}
		else if(ch=='n')
		{
			sum3+=sum2;
		}
	}
	cout<<sum3<<endl;
	return 0;
}

3.蓝桥大使

#include<bits/stdc++.h>
#define int long long
using namespace std;
int n;
vector<pair<int,int>>nums;
bool cmp(const pair<int,int>&x,const pair<int,int>&y)
{
	return (x.first-x.second)>(y.first-y.second);
}
signed main()
{
	cin>>n;
	for(int i=0; i<n; i++)
	{
		int a,b;
		cin>>a>>b;
		nums.push_back({a,b}); //贪心：局部最优 单个班级差值大优先
	}
	sort(nums.begin(),nums.end(),cmp);
	int total=0,task1=n/2;
	for(int i=0; i<n; i++)
	{
		if(i<task1)
		{
			total+=nums[i].first;
		}
		else
		{
			total+=nums[i].second;
		}
	}
	cout<<total<<endl;
	return 0;
}

4.拳头对决

理解清楚题目和样例意思

#include<bits/stdc++.h>
#define int long long
using namespace std;
int n;
int a[100010],b[100010];
signed main()
{
	cin>>n;
	for(int i=1; i<=n; i++) cin>>a[i]; //蓝队每次上场对已经上场红队所有比较
	for(int i=1; i<=n; i++) cin>>b[i]; //红(顺序不可变)
	sort(a+1,a+1+n);	
	int sum=0;
	for(int i=1;i<=n;i++)
	{
		sum+=n-(upper_bound(a+i,a+1+n,b[i])-a)+1; //蓝队大于i的队员才可以遇到红队 
	}
	cout<<sum<<endl;
	return 0;
}