## 435. Non-overlapping Intervals

Given a collection of intervals, find the minimum number of intervals you need to remove to make the rest of the intervals non-overlapping.

Example 1:

```Input: [[1,2],[2,3],[3,4],[1,3]]
Output: 1
Explanation: [1,3] can be removed and the rest of intervals are non-overlapping.
```

Example 2:

```Input: [[1,2],[1,2],[1,2]]
Output: 2
Explanation: You need to remove two [1,2] to make the rest of intervals non-overlapping.
```

Example 3:

```Input: [[1,2],[2,3]]
Output: 0
Explanation: You don't need to remove any of the intervals since they're already non-overlapping.
```

Note:

1. You may assume the interval's end point is always bigger than its start point.
2. Intervals like [1,2] and [2,3] have borders "touching" but they don't overlap each other.

## Rust Solution

``````struct Solution;

impl Solution {
fn erase_overlap_intervals(mut intervals: Vec<Vec<i32>>) -> i32 {
if intervals.is_empty() {
return 0;
}
let n = intervals.len();
intervals.sort_by_key(|v| v);
let mut end = intervals;
let mut res = 0;
for i in 1..n {
if intervals[i] < end {
res += 1;
} else {
end = intervals[i];
}
}
res
}
}

#[test]
fn test() {
let intervals = vec_vec_i32![[1, 2], [2, 3], [3, 4], [1, 3]];
let res = 1;
assert_eq!(Solution::erase_overlap_intervals(intervals), res);
let intervals = vec_vec_i32![[1, 2], [1, 2], [1, 2]];
let res = 2;
assert_eq!(Solution::erase_overlap_intervals(intervals), res);
let intervals = vec_vec_i32![[1, 2], [2, 3]];
let res = 0;
assert_eq!(Solution::erase_overlap_intervals(intervals), res);
}
``````

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