POJ3667 hotel

题目链接：http://poj.org/problem?id=3667

线段树区间合并的入门题，区间合并和就是求什么最长连续什么什么的，所以说需要记录三个值，左起向右最长长度，右起向左最长长度，还有当前区间总最长长度，当前节点的总最长连续长度可由它的左子树和右子树推知，讲的话太麻烦……代码把

#include <iostream>#include <cstdio>#include <cstring>#include <algorithm>using namespace std;#define lson l, m, rt<<1#define rson m+1, r, rt<<1|1const int maxn = 55555;int lsum[maxn<<2], rsum[maxn<<2], msum[maxn<<2], cover[maxn<<2];void PushDown(int rt, int m){    if (cover[rt] != -1){        cover[rt<<1] = cover[rt<<1|1] = cover[rt];        lsum[rt<<1] = rsum[rt<<1] = msum[rt<<1] = cover[rt] ? 0 : m - (m >> 1);        lsum[rt<<1|1] = rsum[rt<<1|1] = msum[rt<<1|1] = cover[rt] ? 0 : (m >> 1);        cover[rt] = -1;    }}void PushUp(int rt, int m){    lsum[rt] = lsum[rt<<1];    rsum[rt] = rsum[rt<<1|1];    if (lsum[rt] == m - (m >> 1)) lsum[rt] += lsum[rt<<1|1];//如果左起向右连续长度等于左子树区间总长度，右子树左起最长连续长度加入进去才是左起总的最长连续长度，下面的右子树同理    if (rsum[rt] == (m >> 1)) rsum[rt] += rsum[rt<<1];    msum[rt] = max(lsum[rt<<1|1] + rsum[rt<<1], max(msum[rt<<1], msum[rt<<1|1]));//推知当前区间总的连续长度}void build(int l, int r, int rt){    lsum[rt] = rsum[rt] = msum[rt] = r - l + 1;    cover[rt] = -1;    if (l == r) return;    int m = (l + r) >> 1;    build(lson);    build(rson);}void update(int ll, int rr, int c, int l, int r, int rt){    if (ll <= l && rr >= r){        lsum[rt] = rsum[rt] = msum[rt] = c ? 0 : r - l + 1;        cover[rt] = c;        return;    }    PushDown(rt, r - l + 1);    int m = (l + r) >> 1;    if (ll <= m) update(ll, rr, c, lson);    if (rr > m) update(ll, rr, c, rson);    PushUp(rt, r - l + 1);}int query(int w, int l, int r, int rt){    if (l == r) return l;    PushDown(rt, r - l + 1);    int m = (l + r) >> 1;    if (msum[rt<<1] >= w) return query(w, lson);    else if (lsum[rt<<1|1] + rsum[rt<<1] >= w) return m - rsum[rt<<1] + 1;    return query(w, rson);}int main(){    int n, m;    while (~scanf("%d%d", &n, &m)){        build(1, n, 1);        while (m--){            int op, a, b;            scanf("%d", &op);            if (op == 1){                scanf("%d", &a);                if (msum[1] < a) printf("0\n");                else{                    int p = query(a, 1, n, 1);                    printf("%d\n", p);                    update(p, p + a - 1, 1, 1, n, 1);                }            }            else{                scanf("%d%d", &a, &b);                update(a, a + b - 1, 0, 1, n, 1);            }        }    }    return 0;}