链接:

题意:

"Help Jimmy" 是在下图所示的场景上完成的游戏。

场景中包括多个长度和高度各不相同的平台。地面是最低的平台，高度为零，长度无限。

Jimmy老鼠在时刻0从高于所有平台的某处开始下落，它的下落速度始终为1米/秒。当Jimmy落到某个平台上时，游戏者选择让它向左还是向右跑，它跑动的速度也是1米/秒。当Jimmy跑到平台的边缘时，开始继续下落。Jimmy每次下落的高度不能超过MAX米，不然就会摔死，游戏也会结束。

设计一个程序，计算Jimmy到底地面时可能的最早时间。

思路:

刚开始考虑记忆化搜索,Dp[i][j], 记录到i平台, j位置落地的最小值, 然后超内存了.

因为每个位置只有左和右,所有考虑走左和走右, 从前一项推出当前项.

代码:

include

//#include <memory.h>

include

include <math.h>

include

include <assert.h>

include

define MINF 0x3f3f3f3f

using namespace std;

typedef long long LL;

const LL MOD = 20090717;

const int MAXN = 1e3+10;

struct Node

{

int l, r;

int h;

bool operator < (const Node& that) const

{

return this->h > that.h;

}

}node[MAXN];

int n, x, y, m;

int Dp[MAXN][2];

void CalLeft(int i)

{

int k = i+1;

while (k <= n && node[i].h - node[k].h <= m)

{

if (node[i].l >= node[k].l && node[i].l <= node[k].r)

{

Dp[i][0] = node[i].h-node[k].h+min(Dp[k][0]+abs(node[i].l-node[k].l), Dp[k][1]+abs(node[i].l-node[k].r));

return;

}

k++;

}

if (node[i].h - node[k].h > m)

Dp[i][0] = MINF;

else

Dp[i][0] = node[i].h;

return;

}

void CalRight(int i)

{

int k = i+1;

while (k <= n && node[i].h-node[k].h <= m)

{

if (node[i].r >= node[k].l && node[i].r <= node[k].r)

{

Dp[i][1] = node[i].h-node[k].h+min(Dp[k][0]+abs(node[i].r-node[k].l), Dp[k][1]+abs(node[i].r-node[k].r));

return;

}

k++;

}

if (node[i].h - node[k].h > m)

Dp[i][1] = MINF;

else

Dp[i][1] = node[i].h;

return;

}

int main()

{

int t;

scanf("%d", &t);

while (t--)

{

memset(Dp, 0, sizeof(Dp));

scanf("%d%d%d%d", &n, &x, &y, &m);

for (int i = 1;i <= n;i++)

scanf("%d%d%d", &node[i].l, &node[i].r, &node[i].h);

sort(node+1, node+1+n);

node[0].l = node[0].r = x;

node[0].h = y;

node[n+1].l = -20000, node[n+1].r = 20000;

node[n+1].h = 0;

for (int i = n;i >= 0;i--)

{

CalLeft(i);

CalRight(i);

}

printf("%d\n", min(Dp[0][0], Dp[0][1]));

}

return 0;

}```c++

巴特西

POJ-1661-Help Jimmy(DP, 递推)

链接:

题意:

思路:

代码:

include

include

include

include

include

include

include

include

include <math.h>

include

include

include <assert.h>

include

include

include

define MINF 0x3f3f3f3f

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