#include <iostream> #include <list> #include <map> using namespace std; class Edge; class Point { public: Edge *left; Edge *right; int index; long long value; Point(int i, long long int v) : index(i), value(v) {} }; class Edge { public: Point *left; Point *right; int leftIndex; int rightIndex; long long leftSum; long long rightSum; Edge(Point *l, Point *r, int lI, int rI) : left(l), right(r), leftIndex(lI), rightIndex(rI) {} int length() const { return rightIndex - leftIndex; } }; struct EdgeComparator { bool operator()(const Edge *edge1, const Edge *edge2) { if(edge1->length() == edge2->length()) { long long sum1 = edge1->left->value + edge1->right->value; long long sum2 = edge2->left->value + edge2->right->value; return sum1 > sum2; } return edge1->length() > edge2->length(); } }; int main() { ios_base::sync_with_stdio(false); cin.tie(NULL); int n; cin >> n; list<Edge *> edges; map<int, Edge *> map; long long leftSum = 0; Point *lastPoint = 0; long long value; for (int i = 0; i < n; i++) { cin >> value; if (value == 0) { continue; } Point *newPoint = new Point(i, value); Edge *edge; if (lastPoint != 0) { edge = new Edge(lastPoint, newPoint, lastPoint->index, newPoint->index); edge->leftSum = leftSum; lastPoint->right = edge; edges.emplace_back(edge); } leftSum += value; newPoint->left = edge; lastPoint = newPoint; } if (leftSum < 0) { cout << -1 << endl; return 0; } long long rightSum = 0; for (;;) { rightSum += lastPoint->value; Edge *edge = lastPoint->left; if (edge == 0) { break; } edge->rightSum = rightSum; lastPoint = edge->left; } edges.sort(EdgeComparator()); int result = 0; for (auto const &edge : edges) { auto upper = map.upper_bound(edge->leftIndex); long long rightSum = edge->rightSum; if (upper != map.end()) { rightSum -= upper->second->rightSum; } auto lower = map.lower_bound(edge->leftIndex); long long leftSum = edge->leftSum; if (lower != map.begin()) { --lower; leftSum -= lower->second->leftSum; } if (leftSum >= 0 && rightSum >= 0) { map.insert(pair<int, Edge *>(edge->leftIndex, edge)); // cout << "Removing egde " << edge->leftIndex << " " << edge->rightIndex << " " << leftSum << " " << rightSum // << " " << (edge->left->value + edge->right->value) << endl; } else { result += edge->length(); // cout << "Using egde " << edge->leftIndex << " " << edge->rightIndex << " " << leftSum << " " << rightSum // << " " << (edge->left->value + edge->right->value) << endl; Point *leftPoint = edge->left; Point *rightPoint = edge->right; leftPoint->right = rightPoint->right; leftPoint->value += rightPoint->value; } } cout << result << endl; 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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 | #include <iostream> #include <list> #include <map> using namespace std; class Edge; class Point { public: Edge *left; Edge *right; int index; long long value; Point(int i, long long int v) : index(i), value(v) {} }; class Edge { public: Point *left; Point *right; int leftIndex; int rightIndex; long long leftSum; long long rightSum; Edge(Point *l, Point *r, int lI, int rI) : left(l), right(r), leftIndex(lI), rightIndex(rI) {} int length() const { return rightIndex - leftIndex; } }; struct EdgeComparator { bool operator()(const Edge *edge1, const Edge *edge2) { if(edge1->length() == edge2->length()) { long long sum1 = edge1->left->value + edge1->right->value; long long sum2 = edge2->left->value + edge2->right->value; return sum1 > sum2; } return edge1->length() > edge2->length(); } }; int main() { ios_base::sync_with_stdio(false); cin.tie(NULL); int n; cin >> n; list<Edge *> edges; map<int, Edge *> map; long long leftSum = 0; Point *lastPoint = 0; long long value; for (int i = 0; i < n; i++) { cin >> value; if (value == 0) { continue; } Point *newPoint = new Point(i, value); Edge *edge; if (lastPoint != 0) { edge = new Edge(lastPoint, newPoint, lastPoint->index, newPoint->index); edge->leftSum = leftSum; lastPoint->right = edge; edges.emplace_back(edge); } leftSum += value; newPoint->left = edge; lastPoint = newPoint; } if (leftSum < 0) { cout << -1 << endl; return 0; } long long rightSum = 0; for (;;) { rightSum += lastPoint->value; Edge *edge = lastPoint->left; if (edge == 0) { break; } edge->rightSum = rightSum; lastPoint = edge->left; } edges.sort(EdgeComparator()); int result = 0; for (auto const &edge : edges) { auto upper = map.upper_bound(edge->leftIndex); long long rightSum = edge->rightSum; if (upper != map.end()) { rightSum -= upper->second->rightSum; } auto lower = map.lower_bound(edge->leftIndex); long long leftSum = edge->leftSum; if (lower != map.begin()) { --lower; leftSum -= lower->second->leftSum; } if (leftSum >= 0 && rightSum >= 0) { map.insert(pair<int, Edge *>(edge->leftIndex, edge)); // cout << "Removing egde " << edge->leftIndex << " " << edge->rightIndex << " " << leftSum << " " << rightSum // << " " << (edge->left->value + edge->right->value) << endl; } else { result += edge->length(); // cout << "Using egde " << edge->leftIndex << " " << edge->rightIndex << " " << leftSum << " " << rightSum // << " " << (edge->left->value + edge->right->value) << endl; Point *leftPoint = edge->left; Point *rightPoint = edge->right; leftPoint->right = rightPoint->right; leftPoint->value += rightPoint->value; } } cout << result << endl; return 0; } |