简单的线段树应用
hdu 1754
/* * c.cpp * * Created on: 2013-10-6 * Author: wangzhu */ #include<cstdio> #include<iostream> using namespace std; #define MAX -1 struct Node { int left, right, max; Node *leftChild, *rightChild; } node[800010]; int getMax(int a, int b) { return a > b ? a : b; } int pos; void build(Node *root, int left, int right) { root->left = left; root->right = right; root->max = MAX; if (left != right) { pos++; root->leftChild = node + pos; pos++; root->rightChild = node + pos; int mid = left + (right - left) / 2; build(root->leftChild, left, mid); build(root->rightChild, mid + 1, right); } } int result; void query(Node *root, int left, int right) { if (root->max <= result) { return; } if (left == root->left && right == root->right) { result = root->max; return; } else { int mid = root->left + (root->right - root->left) / 2; if (right <= mid) { query(root->leftChild, left, right); } else if (left > mid) { query(root->rightChild, left, right); } else { query(root->leftChild, left, mid); query(root->rightChild, mid + 1, right); } } } void update(Node *root, int index, int value) { if (index == root->left && index == root->right) { root->max = value; return; } root->max = getMax(root->max, value); int mid = root->left + (root->right - root->left) / 2; if (index <= mid) { update(root->leftChild, index, value); } else { update(root->rightChild, index, value); } } int main() { int n, m, left, right,value; char c[2]; while (~scanf("%d %d", &n, &m)) { pos = 0; build(node,1, n); for (int i = 1; i <= n; i++) { scanf("%d", &value); update(node,i,value); } for (int i = 0; i < m; i++) { scanf("%s %d %d", c, &left, &right); if (c[0] == 'Q') { result = MAX; query(node, left, right); printf("%d\n", result); } else { update(node, left, right); } } } return 0; }
九度题目1544：数字序列区间最小值
/* * c.cpp * * Created on: 2013-10-6 * Author: wangzhu */ #include<cstdio> #include<iostream> using namespace std; struct Node { int left, right, min; Node *L, *R; }; int arr[100010]; int getMin(int a, int b) { return a > b ? b : a; } Node *build(int left, int right) { Node *root = new Node; root->left = left; root->right = right; if (left != right) { int mid = left + (right - left) / 2; root->L = build(left, mid); root->R = build(mid + 1, right); root->min = getMin(root->L->min, root->R->min); } else { root->L = NULL; root->R = NULL; root->min = getMin(arr[left - 1], arr[right - 1]); } return root; } int query(Node *root, int left, int right) { if (left == root->left && right == root->right) { return root->min; } else { int ret = -1; int mid = root->left + (root->right - root->left) / 2; if (right <= mid) { ret = query(root->L, left, right); } else if (left > mid) { ret = query(root->R, left, right); } else { ret = getMin(query(root->L, left, mid), query(root->R, mid + 1, right)); } return ret; } } int main() { int n, m, left, right; while (~scanf("%d", &n)) { for (int i = 0; i < n; i++) { scanf("%d", &arr[i]); } Node *root; root = build(1, n); scanf("%d", &m); for (int i = 0; i < m; i++) { scanf("%d %d", &left, &right); if (left == right) { printf("%d\n", arr[left - 1]); } else { printf("%d\n", query(root, left, right)); } } } return 0; }