POJ 3277

我是用的线段树做的，时间常数好大，感觉拍的不好。本题要注意统计的方式，而且不要省略pushup操作。

#include <cstdio>
#include <algorithm>
using namespace std;

#define MAXN 40000

int _dirty[MAXN * 4 * 4], *const dirty = &_dirty[-1];

#define recursive_def    int l, int r,int i
#define lsi    i<<1
#define rsi    lsi | 1
#define lsn    l, m, lsi
#define rsn    m+1, r, rsi
#define pushdown    if (dirty[i] >= 0) {
    dirty[lsi] = dirty[rsi] = dirty[i];
    dirty[i] = -1;    
}
#define pushup        if (dirty[i] < 0 && dirty[lsi] == dirty[rsi]) dirty[i] = dirty[lsi];

void update(int L, int R, int h, recursive_def)
{
    if (L<=l && r<=R && dirty[i] >= 0) {
        if (dirty[i] < h) dirty[i] = h;
        return;
    }
    int m = (l+r) >> 1;
    pushdown
    if (L <= m) update(L, R, h, lsn);
    if (R > m) update(L, R, h, rsn);
    pushup
}

int sorted[MAXN*4], sorted_total;

int stt_l, stt_r, stt_h;
long long rslt;

void query0(recursive_def)
{
    if (dirty[i] >= 0) {
//        cout << l << ' '<< r << ' ' << dirty[i] << endl;
        if (dirty[i] == stt_h) stt_r = r;
        else {
            rslt += (long long)stt_h * (sorted[stt_r] - sorted[stt_l] + 1);
            stt_l = l, stt_r = r, stt_h = dirty[i];
        }
        return;
    }
    int m = (l+r) >> 1;
    query0(lsn);
    if (m<r) query0(rsn);
}

long long query(recursive_def)
{
    rslt = stt_h = 0;
    query0(l, r, i);
    rslt += (long long)stt_h *(sorted[stt_r] - sorted[stt_l] + 1);
    return rslt;
}

int N;
int A[MAXN], B[MAXN], H[MAXN];

int main(void)
{
//    freopen("poj3277.txt", "r", stdin);
    scanf("%d", &N);
    sorted_total = 0;
    for(int i=0; i<N; ++i) {
        scanf("%d%d%d", &A[i], &B[i], &H[i]);
        sorted[sorted_total++] = A[i] - 1;
        sorted[sorted_total++] = A[i];
        sorted[sorted_total++] = B[i];
        sorted[sorted_total++] = --B[i];
    }
    sort(sorted, sorted + sorted_total);
    int i, t;
    i = 0;
    for(t=1; t<sorted_total; ++t)
        if (sorted[t-1] != sorted[t])
            sorted[i++] = sorted[t-1];
    sorted[i] = sorted[t-1], sorted_total = i+1;

    dirty[1] = 0;
    for(int i=0; i<N; ++i) {
        A[i] = lower_bound(sorted, sorted + sorted_total, A[i]) - sorted;
        B[i] = lower_bound(sorted, sorted + sorted_total, B[i]) - sorted;
        update(A[i], B[i], H[i], 0, sorted_total-1, 1);
    }
    printf("%lld", query(0, sorted_total-1, 1));
    return 0;
}

3277

Accepted

3524K

1766MS

G++

2238B

2014-07-22 13:01:18