poj1456
题意:有一些货物,每个货物有价值和卖出的截至日期,每天可以卖一个货物,问能卖出的最大价值是多少。
分析:贪心,按利润排序,然后填入一个数组,f[i]表示第i天是否已经被占用。填入f时找到截至日期之前离截至日期最近的一个未被占用的日子。
利用类似并查集的方法优化getanc(i)表示第i天之前最近的未被占用的是第几天
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
usingnamespace std;
#define maxn 10005
struct Product
{
int p, d;
}prod[maxn];
int n;
int father[maxn];
booloperator< (const Product &a, const Product &b)
{
return a.p > b.p;
}
int getanc(int a)
{
if (a <0)
return a;
if (a == father[a])
return a;
return father[a] = getanc(father[a]);
}
bool ins(Product &a)
{
int temp = getanc(a.d -1);
if (temp >=0)
{
father[temp] = getanc(temp -1);
returntrue;
}
returnfalse;
}
int main()
{
//freopen("t.txt", "r", stdin);
while (scanf("%d", &n) != EOF)
{
int t =0;
for (int i=0; i < n; i++)
{
scanf("%d%d", &prod[i].p, &prod[i].d);
if (t < prod[i].d)
t = prod[i].d;
}
sort(prod, prod + n);
for (int i =0; i < t; i++)
father[i] = i;
int ans =0;
for (int i =0; i < n; i++)
if (ins(prod[i]))
ans += prod[i].p;
printf("%d\n", ans);
}
return0;
}
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
usingnamespace std;
#define maxn 10005
struct Product
{
int p, d;
}prod[maxn];
int n;
int father[maxn];
booloperator< (const Product &a, const Product &b)
{
return a.p > b.p;
}
int getanc(int a)
{
if (a <0)
return a;
if (a == father[a])
return a;
return father[a] = getanc(father[a]);
}
bool ins(Product &a)
{
int temp = getanc(a.d -1);
if (temp >=0)
{
father[temp] = getanc(temp -1);
returntrue;
}
returnfalse;
}
int main()
{
//freopen("t.txt", "r", stdin);
while (scanf("%d", &n) != EOF)
{
int t =0;
for (int i=0; i < n; i++)
{
scanf("%d%d", &prod[i].p, &prod[i].d);
if (t < prod[i].d)
t = prod[i].d;
}
sort(prod, prod + n);
for (int i =0; i < t; i++)
father[i] = i;
int ans =0;
for (int i =0; i < n; i++)
if (ins(prod[i]))
ans += prod[i].p;
printf("%d\n", ans);
}
return0;
}