USACO月赛算法解析-优快云博客

本文链接：https://blog.youkuaiyun.com/huangzhengdoc/article/details/78219903
【USC月赛】酸奶工厂
就是简单贪心用一个变量继承最小值然后不停更新就好。
#include<map>
#include<queue>
#include<cmath>
#include<cctype>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<iostream>
#include<algorithm>
#define qread(x) x=read()
#define mes(x,y) memset(x,y,sizeof(x))
#define mpy(x,y) memcpy(x,y,sizeof(x))
#define Maxn 100000
#define INF 2147483647
#define MINF 1073741823
#define LINF 9223372036854775807
#define eps 1e-6
inline int read(){
    char ch=getchar();
    int f=1,x=0;
    while(!(ch>='0'&&ch<='9')){if(ch=='-')f=-1;ch=getchar();}
    while(ch>='0'&&ch<='9'){x=x*10+(ch-'0');ch=getchar();}
    return x*f;
}
int n,c,H[Maxn+1],l,r,ans;
bool check(int x){
	int sum=0,k=0,v=0;
	for(int i=1;i<=n;i++){	
		if(H[i]-H[v]>=x)k++,v=i;
	}
	if(k>=c)return true;
	else return false;
}
int main(){
	qread(n);qread(c);
	l=MINF;r=-MINF;H[0]=-MINF;
	for(int i=1;i<=n;i++)qread(H[i]),l=std::min(l,H[i]),r=std::max(r,H[i]);
	std::sort(H+1,H+n+1);
	while(l<=r){
		int mid=(l+r)/2;
		if(check(mid)==true){
			ans=mid;
			l=mid+1;
		}
		else r=mid-1;
	}
	printf("%lld\n",ans);
}
【USACO月赛】购买饲料
这题就是所有肥料的价格（加上路费）求出来，排个序，取最小的几个就好了呀。#include<map>
#include<queue>
#include<cmath>
#include<cctype>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<iostream>
#include<algorithm>
#define qread(x) x=read()
#define mes(x,y) memset(x,y,sizeof(x))
#define mpy(x,y) memcpy(x,y,sizeof(x))
#define Maxn 100
#define INF 2147483647
#define eps 1e-6
inline int read(){
    char ch=getchar();
    int f=1,x=0;
    while(!(ch>='0'&&ch<='9')){if(ch=='-')f=-1;ch=getchar();}
    while(ch>='0'&&ch<='9'){x=x*10+(ch-'0');ch=getchar();}
    return x*f;
}
int k,e,n,x,y,c,f[Maxn*Maxn+1],ans;
int main(){
	qread(k);qread(e);qread(n);
	f[0]=0;
	for(int i=1;i<=n;i++){
		qread(x);qread(y);qread(c);
		x=e-x;c+=x;
		for(int j=1;j<=y;j++)f[++f[0]]=c;
	}
	std::sort(f+1,f+f[0]+1);
	for(int i=1;i<=k;i++)ans+=f[i];
	printf("%d\n",ans);
}
【USACO月赛】公司利润
这题就是教你怎么用On求最大序列#include<map>
#include<queue>
#include<cmath>
#include<cctype>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<iostream>
#include<algorithm>
#define qread(x) x=read()
#define mes(x,y) memset(x,y,sizeof(x))
#define mpy(x,y) memcpy(x,y,sizeof(x))
#define Maxn 100
#define INF 2147483647
#define eps 1e-6
inline int read(){
    char ch=getchar();
    int f=1,x=0;
    while(!(ch>='0'&&ch<='9')){if(ch=='-')f=-1;ch=getchar();}
    while(ch>='0'&&ch<='9'){x=x*10+(ch-'0');ch=getchar();}
    return x*f;
}
int n,x,sum,ans;
int main(){
	qread(n);
	sum=0;ans=-INF;
	for(int i=1;i<=n;i++){
		qread(x);
		if(sum>0)sum+=x;
		else sum=x;
		ans=std::max(ans,sum);
	}
	printf("%d\n",ans);
}
【USACO赛】奶牛工资
有人比我更跑到快，但是为什么我码得更快还a了。其实这题就是用最大的填充满，然后次大的，然后次次大的，然后次次次大的……然后就这样看看能弄多少遍就能给多少次工资了。还有可以优化的就是我可以一次拿多张而不是一次拿一张。#include<map>
#include<queue>
#include<cmath>
#include<cctype>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<iostream>
#include<algorithm>
#define qread(x) x=read()
#define mes(x,y) memset(x,y,sizeof(x))
#define mpy(x,y) memcpy(x,y,sizeof(x))
#define Maxn 20
#define INF 2147483647
#define eps 1e-6
inline int read(){
    char ch=getchar();
    int f=1,x=0;
    while(!(ch>='0'&&ch<='9')){if(ch=='-')f=-1;ch=getchar();}
    while(ch>='0'&&ch<='9'){x=x*10+(ch-'0');ch=getchar();}
    return x*f;
}
struct Money{
	int x,y;
}M[Maxn+1];
bool Moneycmp(const Money A,const Money B){
	if(A.x>B.x)return true;
	else return false;
}
int n,c,ans;
int main(){
	qread(n);qread(c);
	for(int i=1;i<=n;i++){
		qread(M[i].x);qread(M[i].y);
	}
	std::sort(M+1,M+n+1,Moneycmp);
	ans=0;
	int sum,t;
	for(int i=1;i<=n;i++){
		while(M[i].y>0){
			sum=M[i].x;
			M[i].y--;
			t=1;
			while(t<=n){
				while(M[t].y>0&&sum+M[t].x<=c){
					sum+=M[t].x;
					M[t].y--;
				}
				t++;
			}
			if(sum<c){
				t=n;
				while(t>0){
					while(M[t].y>0&&sum<c){
						sum+=M[t].x;
						M[t].y--;
					}
					t--;
				}
			}
			if(sum>=c)ans++;
		}
	}
	printf("%d\n",ans);
}
【USACO月赛】分期付款。。。
不是贪心的下次做完专题先，大家初赛加油

查看原文：http://hz2016.tk/blog/?p=74