UVa 116 单向TSP（多段图最短路）

https://cn.vjudge.net/problem/UVA-116

题意：给出m行n列的整数矩阵，从第一列任何一个位置出发每次往右，右上或右下走一格，最终到达最后一列，要求经过的整数之和最小。

 #include<iostream>
 #include<algorithm>
 using namespace std;

 const int INF = 0x7FFFFFFF;
 const int maxn =  + ;

 int m, n;
 int a[maxn][maxn];
 int dp[maxn][maxn];
 int next[maxn][maxn];

 int main()
 {
     //freopen("D:\\txt.txt", "r", stdin);
     while (cin >> m >> n && m && n)
     {
         for (int i = ; i < m;i++)
         for (int j = ; j < n; j++)
             cin >> a[i][j];
         int first = ;
         int ans = INF;
         for (int j = n - ; j >= ; j--)
         {
             for (int i = ; i < m; i++)
             {
                 if (j == n - )  dp[i][j] = a[i][j];  //边界
                 else
                 {
                     dp[i][j] = INF;
                     int row[] = { i, i + , i -  };
                     if (i == )       row[] = m - ;
                     if (i == m - )   row[] = ;
                     sort(row, row + );   //重新排序，以便找到字典序最小的
                     for (int k = ; k < ; k++)
                     {
                         int v = dp[row[k]][j + ] + a[i][j];
                         if (v < dp[i][j])      { dp[i][j] = v; ::next[i][j] = row[k];}
                     }
                 }
                 if (j ==  && dp[i][j] < ans)  {
                     ans = dp[i][j]; first = i;
                 }
             }
         }
         cout << first + ;
         for (int i = ::next[first][], j = ; j < n; i = ::next[i][j], j++)
             cout << " " << i + ;
         cout << endl << ans << endl;
     }
     return ;
 }