#include <iostream> #include <vector> #include <set> #include <algorithm> #include <cassert> using namespace std; struct Edge { int to; long long cost; }; bool operator<(const Edge& lhs, const Edge& rhs) { return (lhs.to < rhs.to); } int actual_node = 1; int n, q; vector<long long> gains; vector<set<Edge>> edges; vector<long long> costs; void read() { scanf("%d%d", &n, &q); edges.resize(n+1); gains.resize(n+1); costs.resize(n+1); for(int i = 1; i <= n; ++i) { scanf("%lld", &gains[i]); } for(int i = 1; i < n; ++i) { Edge now; int from; scanf("%d%d%lld", &from, &now.to, &now.cost); edges[from].insert(now); swap(from, now.to); edges[from].insert(now); } } void find_costs(int node) { // printf("DFS node %d, cost %d\n", node, cost); for(auto next: edges[node]) { if (costs[next.to] == -1) { costs[next.to] = costs[node] + next.cost; find_costs(next.to); } } } void find_costs() { std::fill(costs.begin(), costs.end(), -1); costs[actual_node] = 0; find_costs(actual_node); } void find_best() { // printf("Iteration. Actual node = %d\n", actual_node); find_costs(); // -delta, node vector<pair<long long, int>> delta; for(int i = 1; i <= n; ++i) { // printf("[%d]: %d %d\n", i, costs[i], gains[i] - costs[i]); if (i == actual_node) continue; delta.push_back(make_pair(costs[i]-gains[i], i)); } std::sort(delta.begin(), delta.end()); // for(auto i : delta) { // printf ("%lld %d\n", -i.first, i.second); // } // printf("Actual night in %d, gain %lld\n", delta[0].second, -delta[0].first); actual_node = delta[0].second; } int main() { read(); for(int _ = 0; _ < q; ++_) { int operation; scanf("%d", &operation); // printf("Operation %d\n", operation); if (operation == 1) { int node; long long val; scanf("%d%lld", &node, &val); gains[node] = val; } if (operation == 2) { Edge update; int from, to; scanf("%d%d%lld", &from, &to, &update.cost); // printf("Update cost (%d %d): %d\n", from, to, update.cost); update.to = to; auto search = edges[from].find(update); assert(search != edges[from].end()); edges[from].erase(search); edges[from].insert(update); update.to = from; search = edges[to].find(update); assert(search != edges[to].end()); edges[to].erase(search); edges[to].insert(update); } find_best(); printf("%d ", actual_node); } printf("\n"); return 0; }
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 | #include <iostream> #include <vector> #include <set> #include <algorithm> #include <cassert> using namespace std; struct Edge { int to; long long cost; }; bool operator<(const Edge& lhs, const Edge& rhs) { return (lhs.to < rhs.to); } int actual_node = 1; int n, q; vector<long long> gains; vector<set<Edge>> edges; vector<long long> costs; void read() { scanf("%d%d", &n, &q); edges.resize(n+1); gains.resize(n+1); costs.resize(n+1); for(int i = 1; i <= n; ++i) { scanf("%lld", &gains[i]); } for(int i = 1; i < n; ++i) { Edge now; int from; scanf("%d%d%lld", &from, &now.to, &now.cost); edges[from].insert(now); swap(from, now.to); edges[from].insert(now); } } void find_costs(int node) { // printf("DFS node %d, cost %d\n", node, cost); for(auto next: edges[node]) { if (costs[next.to] == -1) { costs[next.to] = costs[node] + next.cost; find_costs(next.to); } } } void find_costs() { std::fill(costs.begin(), costs.end(), -1); costs[actual_node] = 0; find_costs(actual_node); } void find_best() { // printf("Iteration. Actual node = %d\n", actual_node); find_costs(); // -delta, node vector<pair<long long, int>> delta; for(int i = 1; i <= n; ++i) { // printf("[%d]: %d %d\n", i, costs[i], gains[i] - costs[i]); if (i == actual_node) continue; delta.push_back(make_pair(costs[i]-gains[i], i)); } std::sort(delta.begin(), delta.end()); // for(auto i : delta) { // printf ("%lld %d\n", -i.first, i.second); // } // printf("Actual night in %d, gain %lld\n", delta[0].second, -delta[0].first); actual_node = delta[0].second; } int main() { read(); for(int _ = 0; _ < q; ++_) { int operation; scanf("%d", &operation); // printf("Operation %d\n", operation); if (operation == 1) { int node; long long val; scanf("%d%lld", &node, &val); gains[node] = val; } if (operation == 2) { Edge update; int from, to; scanf("%d%d%lld", &from, &to, &update.cost); // printf("Update cost (%d %d): %d\n", from, to, update.cost); update.to = to; auto search = edges[from].find(update); assert(search != edges[from].end()); edges[from].erase(search); edges[from].insert(update); update.to = from; search = edges[to].find(update); assert(search != edges[to].end()); edges[to].erase(search); edges[to].insert(update); } find_best(); printf("%d ", actual_node); } printf("\n"); return 0; } |