UVA 1232 - SKYLINE(线段树)

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UVA 1232 - SKYLINE

题目链接

题意:按顺序建房，在一条线段上，每个房子一个高度，要求出每间房子建上去后的轮廓线

思路：线段树延迟更新，一个setv作为高度的懒标记，此外还要在开一个cover表示当前结点一下是否都为同一高度

代码：

#include <cstdio>#include <cstring>#include <algorithm>using namespace std;#define lson(x) ((x<<1)+1)#define rson(x) ((x<<1)+2)const int N = 100005;int t, n;struct Node {    int l, r, h, setv;    bool cover;    Node() {}    Node(int l, int r) {this->l = l; this->r = r;h = 0; setv = 0; cover = true;    }} node[4 * N];void pushup(int x) {    node[x].cover = ((node[lson(x)].h == node[rson(x)].h) && node[lson(x)].cover && node[rson(x)].cover);    node[x].h = node[lson(x)].h;}void pushdown(int x) {    node[lson(x)].setv = max(node[lson(x)].setv, node[x].setv);    node[rson(x)].setv = max(node[rson(x)].setv, node[x].setv);    node[lson(x)].h = max(node[lson(x)].setv, node[lson(x)].h);    node[rson(x)].h = max(node[rson(x)].setv, node[rson(x)].h);}void build(int l, int r, int x = 0) {    node[x] = Node(l, r);    if (l == r) return;    int mid = (l + r) / 2;    build(l, mid, lson(x));    build(mid + 1, r, rson(x));}int query(int l, int r, int v, int x = 0) {    if (node[x].cover && node[x].h > v) return 0;    if (node[x].l >= l && node[x].r <= r && node[x].cover) {node[x].setv = v;node[x].h = v;return node[x].r - node[x].l + 1;    }    int mid = (node[x].l + node[x].r) / 2;    int ans = 0;    pushdown(x);    if (l <= mid) ans += query(l, r, v, lson(x));    if (r > mid) ans += query(l, r, v, rson(x));    pushup(x);    return ans;}int main() {    scanf("%d", &t);    while (t--) {scanf("%d", &n);build(1, N - 1);int l, r, h;int ans = 0;while (n--) {    scanf("%d%d%d", &l, &r, &h);    ans += query(l, r - 1, h);}printf("%d\n", ans);    }    return 0;}

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