poj 1456 - Supermarket(贪心+并查集)

const int M = 10005;
struct Node
{
int pi, di;
bool operator < (const Node &tmp)const
{
return pi>tmp.pi;
}
}node[M];
int p[M];
int find(int x) { return p[x]==x?x:find(p[x]); }
int main()
{
int n, maxpi;
while(~scanf("%d", &n))
{
maxpi = 0;
for(int i = 0; i < n; ++i)
scanf("%d%d", &node[i].pi, &node[i].di), maxpi = max(maxpi, node[i].pi);
sort(node, node+n);
int ans = 0;
for(int i = 0; i <= maxpi; ++i) p[i] = i;
for(int i = 0; i < n; ++i)
if(find(node[i].di)>0)
{
ans += node[i].pi;
int tmp = find(node[i].di);
int x = find(tmp);
int y = find(tmp-1);
p[x] = y;
}

printf("%d\n", ans);
}
return 0;
}