```
int r = n - 1;
while (r > 0 && a[r] < a[r - 1]) {
r--;
}
cout << r << endl;
```
……挺无语的，符号错了，正解：
```
int r = n - 1;
while (r > 0 && a[r] < a[r + 1]) {
r--;
}
cout << r << endl;
```
本人已AC
此贴结
by Mark_M @ 2023-01-28 19:22:45