The second return is to debug while running test input,O(n)time, O(1)space

```
/**
* @param {number[][]} points
* @return {number}
*/
var findMinArrowShots = function(points) {
let rtn = 0;
points.sort(function(a,b){return a[0] - b[0];});
for(let i = 0; i< points.length; i++, rtn++){
while(i < points.length - 1 && points[i][1] >= points[i+1][0]){
points[i+1] = [Math.max(points[i][0],points[i+1][0]), Math.min(points[i][1],points[i+1][1])];
i++;
}
}
return rtn;
return [points,rtn];
};
```