LC769. Max Chunks to make sorted

key: mx == i.

public int maxChunksToSorted(int[] arr) {
    int res = 0, mx = 0;
    for (int i = 0; i < arr.length; ++i) {
        mx = Math.max(mx, arr[i]);
        if (mx == i) ++res;
    }
    return res;
}