T1:
这题又是动态题面问题，一开始连求什么都没告诉你......
当时自然没有看了，现在没人做没人改......
官方题解:
标程:
1 #include <iostream> 2 #include <cstdio> 3 #include <map> 4 #include <set> 5 #include <queue> 6 #include <vector> 7 #include <cstring> 8 #include <cstdlib> 9 #include <algorithm> 10 #define rep(i,a,b) for(int i = a; i <= b; i++) 11 #define dep(i,a,b) for(int i = a; i >= b; i--) 12 #define Rep(i,a) for(int i = 0; i < a; i++) 13 #define pb(a) push_back(a) 14 #define mp(a,b) make_pair(a,b) 15 #define ab(x) ((x) < 0 ? -(x) : (x)) 16 using namespace std; 17 typedef long long LL; 18 typedef map<int, int>::iterator mit; 19 typedef set<int>::iterator sit; 20 typedef pair<int, int> pii; 21 #define x first 22 #define y second 23 const int N = 1e5, E = 1e5, inf = 1e9; 24 int n, m, q, k, S, T, C[E << 1]; 25 struct edge{ int to, pre, w, c; } e[E << 1]; int u[N], l = 1;//l==1! 26 void ins(int a, int b, int w, int c) { e[++l] = (edge){b, u[a], w, c}, u[a] = l; } 27 void insert(int a, int b, int w, int c) { ins(a, b, w, c), ins(b, a, 0, -c); } 28 #define v e[i].to 29 #define reg(i,a) for(int i = u[a]; i; i = e[i].pre) 30 #define ec e[i].c 31 #define ew e[i].w 32 int cost, h[N], c; 33 bool vis[N]; 34 bool dij() { 35 static pii q[E]; int l = 1; 36 rep(i,S,T) h[i] = inf, vis[i] = false; q[1] = mp(-(h[S] = 0), S); 37 while (l) { 38 int x = q[1].y; pop_heap(q + 1, q + l + 1), l--; 39 if (vis[x] || h[x] == inf) continue; vis[x] = true; 40 reg(i,x) if (ew && h[x] + ec < h[v]) { 41 h[v] = h[x] + ec; 42 q[++l] = mp(-h[v], v); push_heap(q + 1, q + l + 1); 43 } 44 } 45 rep(x,S,T) reg(i,x) ec -= h[v] - h[x]; 46 c += h[T]; 47 return h[T] < inf; 48 } 49 int cur[N]; 50 int dfs(int x, int f) { 51 if (x == T) return f; 52 int w, used = 0; vis[x] = true; 53 for(int i = cur[x]; i; i = e[i].pre) if (ew && !ec && !vis[v] && ~h[v]) { 54 w = min(ew, f - used), w = dfs(v, w); 55 ew -= w; if (ew) cur[x] = i; 56 e[i ^ 1].w += w; 57 used += w; if (used == f) break; 58 } 59 vis[x] = false; 60 if (!used) h[x] = -1; 61 return used; 62 } 63 void flow() { 64 while (dij()) { 65 rep(i,S,T) cur[i] = u[i], vis[i] = false; 66 int w = dfs(S, inf); 67 cost += c * w; 68 } 69 } 70 71 int ans = 0, d[N]; 72 void addedge(int a, int b, int c) { 73 ans += c; 74 insert(a, b, q, 0); d[b]++, d[a]--; insert(b, a, 1, c * 100); 75 } 76 int a[N], b[N]; 77 map<int, int> f; 78 int check(int c1) { 79 if (f.find(c1) != f.end()) return f[c1]; 80 static int u1[N], l1; 81 rep(i,S,T) u1[i] = u[i]; l1 = l; 82 rep(i,1,l) C[i] = e[i].c; 83 rep(i,1,q) insert(b[i], a[i], 1, c1 * 100 + 1); 84 cost = c = 0; flow(); 85 rep(i,S,T) u[i] = u1[i]; l = l1; 86 rep(i,1,l) e[i].c = C[i]; 87 for(int i = 2; i <= l; i += 2) 88 e[i].w += e[i ^ 1].w, e[i ^ 1].w = 0; 89 return f[c1] = cost; 90 } 91 92 void solve() { 93 int l = -1, r = 1e5 + 10; 94 while (l + 1 < r) { 95 int mid = (l + r) >> 1; 96 if (check(mid) % 100 <= k) r = mid; else l = mid; 97 } 98 int C = check(r); 99 ans = ans - C / 100 + r * k; 100 } 101 102 int main() { 103 scanf("%d%d%d%d",&n,&m,&q,&k); 104 S = 0, T = n + 1; 105 rep(i,1,m) { 106 int a, b, c; scanf("%d%d%d",&a,&b,&c); 107 addedge(a, b, c); 108 } 109 rep(i,1,n) if (d[i] > 0) insert(S, i, d[i], 0); else if (d[i] < 0) insert(i, T, -d[i], 0); 110 rep(i,1,q) scanf("%d%d",a + i, b + i); 111 solve(); 112 printf("%d\n", ans); 113 return 0; 114 }