hdu 5493 Queue（线段树）

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题目链接：hdu 5493 Queue

解题思路

将人头按照从小到大排序，每次优先放小的，尽量靠前。
用线段树维护空位，每次判断前隔k人靠前还是后隔k人靠前。

代码

#include <cstdio>#include <cstring>#include <vector>#include <algorithm>using namespace std;const int maxn = 100005;typedef pair<int,int> pii;#define lson(x) ((x)<<1)#define rson(x) (((x)<<1)|1)struct SegTree {    int lc[maxn<<2], rc[maxn<<2], s[maxn<<2];    void pushup(int u) { s[u] = s[lson(u)] + s[rson(u)]; }    void build (int u, int l, int r) {        lc[u] = l, rc[u] = r, s[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 x) {        if (lc[u] == rc[u]) {            s[u] = 0;            return;        }        int mid = (lc[u] + rc[u])>>1;        if (x <= mid) modify(lson(u), x);        else modify(rson(u), x);        pushup(u);    }    int query(int u, int x) {        if (lc[u] == rc[u])            return lc[u];        int mid = (lc[u] + rc[u])>>1;        if (s[lson(u)] >= x) return query(lson(u), x);        else return query(rson(u), x - s[lson(u)]);    }}T;int N, A[maxn];vector<pii> G;void init () {    int h, k;    scanf("%d", &N);    G.clear();    for (int i = 1; i <= N; i++) {        scanf("%d%d", &h, &k);        G.push_back(make_pair(h, k));    }    sort(G.begin(), G.end());    T.build(1, 1, N);}bool solve () {    for (int i = 0; i < N; i++) {        if (G[i].second >= N-i) return false;        int pre = G[i].second + 1, suf = N-i-G[i].second;        int pos = min(T.query(1, pre), T.query(1, suf));        A[pos] = G[i].first;        T.modify(1, pos);    }    for (int i = 1; i <= N; i++)        printf(" %d", A[i]);    printf("\n");    return true;}int main () {    int cas;    scanf("%d", &cas);    for (int kcas = 1; kcas <= cas; kcas++) {        init();        printf("Case #%d:", kcas);        if (!solve()) printf(" impossible\n");    }    return 0;}

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