hdu 4614 Vases and Flowers（线段树）

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题目链接：hdu 4614 Vases and Flowers
解题思路

用线段树维护空位。
代码

#include <cstdio>#include <cstring>#include <algorithm>using namespace std;#define lson(x) (x<<1)#define rson(x) ((x<<1)|1)const int maxn = 50005;int lc[maxn<<2], rc[maxn<<2], siz[maxn<<2], laz[maxn<<2];int length(int u) { return rc[u] - lc[u] + 1; }void maintain(int u, int v) {    laz[u] = v;    siz[u] = laz[u] * length(u);}void pushup(int u) { siz[u] = siz[lson(u)] + siz[rson(u)]; }void pushdown(int u) {    if (laz[u] != -1) {        maintain(lson(u), laz[u]);        maintain(rson(u), laz[u]);        laz[u] = -1;    }}void build (int u, int l, int r) {    lc[u] = l, rc[u] = r, siz[u] = 0, laz[u] = -1;    if (l == r) return;    int mid = (l + r) >> 1;    build(lson(u), l, mid);    build(rson(u), mid+1, r);    pushup(u);}void modify(int u, int l, int r, int v) {    if (l <= lc[u] && rc[u] <= r) {        maintain(u, v);        return;    }    pushdown(u);    int mid = (lc[u] + rc[u]) >> 1;    if (l <= mid) modify(lson(u), l, r, v);    if (r > mid) modify(rson(u), l, r, v);    pushup(u);}int query(int u, int l, int r) {    if (l > r) return 0;    if (l <= lc[u] && rc[u] <= r)        return siz[u];    pushdown(u);    int mid = (lc[u] + rc[u]) >> 1, ret = 0;    if (l <= mid) ret += query(lson(u), l, r);    if (r > mid) ret += query(rson(u), l, r);    pushup(u);    return ret;}int find(int u, int k) {    if (lc[u] == rc[u]) return lc[u];    pushdown(u);    int rest = length(lson(u)) - siz[lson(u)], ret;    if (rest >= k) ret =  find(lson(u), k);    else ret = find(rson(u), k - rest);    pushup(u);    return ret;}int N, M;int main () {    int cas;    scanf("%d", &cas);    while (cas--) {        scanf("%d%d", &N, &M);        build(1, 0, N-1);        int k, l, r;        while (M--) {            scanf("%d%d%d", &k, &l, &r);            if (k == 1) {                int rest = N - l - query(1, l, N-1);                if (rest == 0)                    printf("Can not put any one.\n");                else {                    int pre = l - query(1, 0, l-1);                    int posl = find(1, pre + 1);                    int posr = find(1, pre + min(r, rest));                    modify(1, posl, posr, 1);                    printf("%d %d\n", posl, posr);                }            } else {                printf("%d\n", query(1, l, r));                modify(1, l, r, 0);            }        }        printf("\n");    }    return 0;}
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