98 lines
2.3 KiB
C++
98 lines
2.3 KiB
C++
#include <stdio.h>
|
||
#include <stdlib.h>
|
||
|
||
#define MAXN 1010
|
||
#define INF 9000000
|
||
|
||
typedef struct platform{
|
||
int x1;
|
||
int x2;
|
||
int high;
|
||
}Platform;
|
||
|
||
int compare (const void * p, const void * q){
|
||
Platform * p1 = (Platform *)p;
|
||
Platform * q1 = (Platform *)q;
|
||
return p1->high - q1->high;
|
||
}
|
||
|
||
int Min (int a, int b){
|
||
return (a < b) ? a : b;
|
||
}
|
||
|
||
int N, X, Y, MAX;
|
||
Platform plat[MAXN];
|
||
int dp[MAXN][2]; //dp[i][0]、dp[i][1]分别表示从第i个平台左、右边到地面的最短时间
|
||
|
||
void LeftMinTime (int i){ //计算从平台i左边到地面的最短时间
|
||
int k = i - 1;
|
||
while (k > 0 && plat[i].high - plat[k].high <= MAX){
|
||
//如果平台i左边下面有平台，且两者相距不超过MAX
|
||
if (plat[i].x1 >= plat[k].x1 && plat[i].x1 <= plat[k].x2){
|
||
dp[i][0] = plat[i].high - plat[k].high +
|
||
Min (plat[i].x1 - plat[k].x1 + dp[k][0], plat[k].x2 - plat[i].x1 + dp[k][1]);
|
||
return;
|
||
}
|
||
else
|
||
--k;
|
||
}
|
||
//如果平台i左边下面没有平台，或者两者相距超过了MAX
|
||
if (plat[i].high - plat[k].high > MAX)
|
||
dp[i][0] = INF;
|
||
else
|
||
dp[i][0] = plat[i].high;
|
||
}
|
||
|
||
void RightMinTime (int i){ //计算从平台i右边到地面的最短时间
|
||
int k = i - 1;
|
||
while (k > 0 && plat[i].high - plat[k].high <= MAX){
|
||
//如果平台i右边下面有平台，且两者相距不超过MAX
|
||
if (plat[i].x2 >= plat[k].x1 && plat[i].x2 <= plat[k].x2){
|
||
dp[i][1] = plat[i].high - plat[k].high +
|
||
Min (plat[i].x2 - plat[k].x1 + dp[k][0], plat[k].x2 - plat[i].x2 + dp[k][1]);
|
||
return;
|
||
}
|
||
else
|
||
--k;
|
||
}
|
||
//如果平台i右边下面没有平台，或者两者相距超过了MAX
|
||
if (plat[i].high - plat[k].high > MAX)
|
||
dp[i][1] = INF;
|
||
else
|
||
dp[i][1] = plat[i].high;
|
||
}
|
||
|
||
int ShortestTime (){
|
||
int i, j;
|
||
|
||
for (i=1; i<=N+1; ++i){
|
||
LeftMinTime (i);
|
||
RightMinTime (i);
|
||
}
|
||
return Min (dp[N+1][0], dp[N+1][1]);
|
||
}
|
||
|
||
int main(void){
|
||
int t;
|
||
int i;
|
||
while (scanf ("%d", &t) != EOF){
|
||
while (t-- != 0){
|
||
scanf ("%d%d%d%d", &N, &X, &Y, &MAX);
|
||
for (i=1; i<=N; ++i){
|
||
scanf ("%d%d%d", &plat[i].x1, &plat[i].x2, &plat[i].high);
|
||
}
|
||
plat[0].high = 0;
|
||
plat[0].x1 = -20000;
|
||
plat[0].x2 = 20000;
|
||
plat[N+1].high = Y;
|
||
plat[N+1].x1 = X;
|
||
plat[N+1].x2 = X;
|
||
//根据平台高度按从低到高排序
|
||
qsort (plat, N+2, sizeof(Platform), compare);
|
||
printf ("%d\n", ShortestTime());
|
||
}
|
||
}
|
||
|
||
return 0;
|
||
}
|