C. Journey
链接：
http://codeforces.com/contest/721/problem/C
题意：
给你一个n点m边的图，让你从1走到n，找到一条经过尽量多点的路径，且路径边权和小于等于T
然后输出路径。
题解：
直接DP，DP[i][j]表示在i点，当前经过了j个点的最小代价是多少
代码：
1 #include <iostream> 2 #include <stack> 3 #include <cstring> 4 using namespace std; 5 6 const int maxn = 5e3 + 7; 7 struct Edge { int u, v, t; }E[maxn]; 8 int dp[maxn][maxn]; 9 int pre[maxn][maxn]; 10 stack<int> ans; 11 12 int main() 13 { 14 int n, m, T; 15 cin >> n >> m >> T; 16 for (int i = 0; i < m; i++) 17 cin >> E[i].u >> E[i].v >> E[i].t; 18 memset(dp, 0x3f, sizeof(dp)); 19 memset(pre, -1, sizeof(pre)); 20 dp[1][1] = 0; 21 int pos; 22 for (int i = 2; i <= n; i++) { 23 for (int j = 0; j < m; j++) { 24 int u = E[j].u; 25 int v = E[j].v; 26 int t = E[j].t; 27 if (dp[i - 1][u] + t < dp[i][v]) { 28 dp[i][v] = dp[i - 1][u] + t; 29 pre[i][v] = u; 30 } 31 } 32 if (dp[i][n] <= T) pos = i; 33 } 34 cout << pos << endl; 35 int u = n; 36 while (u != -1) { 37 ans.push(u); 38 u = pre[pos--][u]; 39 } 40 while (!ans.empty()){ 41 cout << ans.top() << " "; 42 ans.pop(); 43 } 44 return 0; 45 }