Bzoj1658 [usaco 2006 Mar] water slides

A good day is coming!

First, I was abused as usaco's silver question... It took two days to complete.

Finally, I found that sort forgot + 1 (start + cnt1 (+ 1) and asked the Administrator for the data...

The practice is not difficult to think about:

(1) divide points into two types: Outbound> inbound> outbound

(2) run the network stream once.

It seems that t is really miserable... Then improve:

It is better to discover that two line segments do not overlap (that is, simply greedy thinking)

As a result, the two types of vertices are sorted, and the matching answer must be the smallest one.

 

 1 /************************************************************** 2     Problem: 1658 3     User: rausen 4     Language: C++ 5     Result: Accepted 6     Time:32 ms 7     Memory:1040 kb 8 ****************************************************************/ 9  10 #include <cstdio>11 #include <algorithm>12  13 using namespace std;14  15 int n, m, ans, cnt1, cnt2, X, Y;16 int deg[15000], start[15000], stop[15000], pos[15000];17  18 int main(){19     scanf("%d%d", &n, &m);20     for (int i = 1; i <= n; ++i)21         scanf("%d", pos + i);22     for (int i = 1; i <= m; ++i){23         scanf("%d%d", &X, &Y);24         ++deg[X], --deg[Y];25     }26  27     for (int i = 1; i <= n; ++i){28         for(; deg[i] > 0; --deg[i]) start[++cnt1] = pos[i];29         for(; deg[i] < 0; ++deg[i]) stop[++cnt2] = pos[i];30     }31  32     sort(start + 1, start + cnt1 + 1);33     sort(stop + 1, stop + cnt2 + 1);34      35     for (int i = 1; i <= cnt1; ++i)36         ans += abs(start[i] - stop[i]);37     printf("%d\n", ans);38     return 0;39 }

View code

 

Bzoj1658 [usaco 2006 Mar] water slides