LA 3983 Robotruck

这道题感觉挺吃力的，还用到了我不熟悉的优先队列

题目中的推导也都看明白了，总之以后还要多体会才是

这里用优先对列的原因就是因为要维护一个滑动区间的最小值，比如在区间里２在１的前面，２在离开这个滑动区间会一直被１给“压迫”着，所以这个２是无用的，应当及时删除。这样的话剩下的元素都是递增的，优先队列也称单调队列也因此得名。

先把代码贴上：

//#define LOCAL
#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;

const int maxn = 100000 + 10;
int x[maxn], y[maxn];
int total_dist[maxn], total_weight[maxn], dist2origin[maxn];
int q[maxn], d[maxn];

int func(int i)
{
    return d[i] - total_dist[i+1] + dist2origin[i+1];
}

int main(void)
{
    #ifdef LOCAL
        freopen("3983in.txt", "r", stdin);
    #endif

    int T;
    scanf("%d", &T);
    while(T--)
    {
        int c, n, w, front, rear;
        scanf("%d%d", &c, &n);
        total_dist[0] = total_weight[0] = x[0] = y[0] = 0;
        for(int i = 1; i <= n; ++i)
        {
            scanf("%d%d%d", &x[i], &y[i], &w);
            dist2origin[i] = x[i] + y[i];
            total_dist[i] = total_dist[i-1] + abs(x[i] - x[i-1]) + abs(y[i] - y[i-1]);
            total_weight[i] = total_weight[i-1] + w;
        }
        front = rear = 1;
        for(int i = 1; i <= n; ++i)
        {
            while(front <= rear && total_weight[i] - total_weight[q[front]] > c)
                ++front;
            d[i] = func(q[front]) + total_dist[i] + dist2origin[i];
            while(front <= rear && func(q[rear]) >= func(i))
                --rear;
            q[++rear] = i;
        }
        printf("%d
", d[n]);
        if(T)    printf("
");
    }
    return 0;
}