AtCoder Grand Contest 036
D
Negative Cycle
AtCoder
⌀ 3326
原题
← CE →
翻译中…

Problem Statement

翻译中…

We have a weighted directed graph with $N$ vertices numbered $0$ to $N-1$.

翻译中…

The graph initially has $N-1$ edges. The $i$-th edge ($0 \leq i \leq N-2$) is directed from Vertex $i$ to Vertex $i+1$ and has a weight of $0$.

翻译中…

Snuke will now add a new edge $(i → j)$ for every pair $i, j$ ($0 \leq i,j \leq N-1,\ i \neq j$). The weight of the edge will be $-1$ if $i < j$, and $1$ otherwise.

翻译中…

Ringo is a boy. A negative cycle (a cycle whose total weight is negative) in a graph makes him sad. He will delete some of the edges added by Snuke so that the graph will no longer contain a negative cycle. The cost of deleting the edge $(i → j)$ is $A_{i,j}$. He cannot delete edges that have been present from the beginning.

翻译中…

Find the minimum total cost required to achieve Ringo's objective.

翻译中…

Constraints

翻译中…
  • $3 \leq N \leq 500$
  • $1 \leq A_{i,j} \leq 10^9$
  • All values in input are integers.
翻译中…

Input

翻译中…

Input is given from Standard Input in the following format:

翻译中…

N
A_{0,1} A_{0,2} A_{0,3} \cdots A_{0,N-1}
A_{1,0} A_{1,2} A_{1,3} \cdots A_{1,N-1}
A_{2,0} A_{2,1} A_{2,3} \cdots A_{2,N-1}
\vdots
A_{N-1,0} A_{N-1,1} A_{N-1,2} \cdots A_{N-1,N-2}

翻译中…

Output

翻译中…

Print the minimum total cost required to achieve Ringo's objective.

翻译中…

样例

Input #1
3
2 1
1 4
3 3
Output #1
2
If we delete the edge $(0 → 1)$ added by Snuke, the graph will no longer contain a negative cycle. The cost will be $2$ in this case, which is the minimum possible.
Input #2
4
1 1 1
1 1 1
1 1 1
1 1 1
Output #2
2
If we delete the edges $(1 → 2)$ and $(3 → 0)$ added by Snuke, the graph will no longer contain a negative cycle. The cost will be $1+1=2$ in this case, which is the minimum possible.
Input #3
10
190587 2038070 142162180 88207341 215145790 38 2 5 20
32047998 21426 4177178 52 734621629 2596 102224223 5 1864
41 481241221 1518272 51 772 146 8805349 3243297 449
918151 126080576 5186563 46354 6646 491776 5750138 2897 161
3656 7551068 2919714 43035419 495 3408 26 3317 2698
455357 3 12 1857 5459 7870 4123856 2402 258
3 25700 16191 102120 971821039 52375 40449 20548149 16186673
2 16 130300357 18 6574485 29175 179 1693 2681
99 833 131 2 414045824 57357 56 302669472 95
8408 7 1266941 60620177 129747 41382505 38966 187 5151064
Output #3
2280211
题目信息
题号
agc036_d
时间限制
2 s
内存限制
1024 MB

题面与样例版权归 AtCoder 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。