# How to Solve the Car Pooling Challenge in Java

## The challenge

You are driving a vehicle that has `capacity` empty seats initially available for passengers.  The vehicle only drives east (ie. it cannot turn around and drive west.)

Given a list of `trips``trip[i] = [num_passengers, start_location, end_location]` contains information about the `i`-th trip: the number of passengers that must be picked up, and the locations to pick them up and drop them off.  The locations are given as the number of kilometers due east from your vehicle’s initial location.

Return `true` if and only if it is possible to pick up and drop off all passengers for all the given trips.

Example 1:

`Input: trips = [[2,1,5],[3,3,7]], capacity = 4Output: false`

Example 2:

`Input: trips = [[2,1,5],[3,3,7]], capacity = 5Output: true`

Example 3:

`Input: trips = [[2,1,5],[3,5,7]], capacity = 3Output: true`

Example 4:

`Input: trips = [[3,2,7],[3,7,9],[8,3,9]], capacity = 11Output: true`

Constraints:

1. `trips.length <= 1000`
2. `trips[i].length == 3`
3. `1 <= trips[i][0] <= 100`
4. `0 <= trips[i][1] < trips[i][2] <= 1000`
5. `1 <= capacity <= 100000`

## The solution in Java

```.wp-block-code{border:0;padding:0}.wp-block-code>div{overflow:auto}.shcb-language{border:0;clip:rect(1px,1px,1px,1px);-webkit-clip-path:inset(50%);clip-path:inset(50%);height:1px;margin:-1px;overflow:hidden;padding:0;position:absolute;width:1px;word-wrap:normal;word-break:normal}.hljs{box-sizing:border-box}.hljs.shcb-code-table{display:table;width:100%}.hljs.shcb-code-table>.shcb-loc{color:inherit;display:table-row;width:100%}.hljs.shcb-code-table .shcb-loc>span{display:table-cell}.wp-block-code code.hljs:not(.shcb-wrap-lines){white-space:pre}.wp-block-code code.hljs.shcb-wrap-lines{white-space:pre-wrap}.hljs.shcb-line-numbers{border-spacing:0;counter-reset:line}.hljs.shcb-line-numbers>.shcb-loc{counter-increment:line}.hljs.shcb-line-numbers .shcb-loc>span{padding-left:.75em}.hljs.shcb-line-numbers .shcb-loc::before{border-right:1px solid #ddd;content:counter(line);display:table-cell;padding:0 .75em;text-align:right;-webkit-user-select:none;-moz-user-select:none;-ms-user-select:none;user-select:none;white-space:nowrap;width:1%}```class Solution {
public boolean carPooling(int[][] trips, int capacity) {
/*
trips[i][0] = amount of people
trips[i][1] = get on
trips[i][2] = get off
*/

int[] stops = new int[1001];

for (int[] t : trips) {
stops[t[1]] += t[0];
stops[t[2]] -= t[0];
}

for (int i=0; capacity>=0 && i<1001; i++)
capacity -= stops[i];

return capacity >= 0;

}
}
```Code language: Java (java)```
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