// 单调栈：存储索引（而非值），栈内索引对应的nums值保持「单调递减」
There are times when it feels as though the entirety of British horse racing exists in a state of perma-gloom, bewailing an ageing fanbase, declining attendances and a moribund, factional leadership. It is, so the narrative goes, a sport in slow but irreversible decline, waiting for the inevitable moment in 10 or 20 years’ time when someone finally comes along to turn out the lights.
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struct foo { int length; char d[0]; } *s = malloc(sizeof(int)+n);
Transforms don't execute until the consumer pulls. There's no eager evaluation, no hidden buffering. Data flows on-demand from source, through transforms, to the consumer. If you stop iterating, processing stops.
If the A* calculation for a shortcut (in Step 3) finds it's now impassable, or if its actual detailed cost is significantly different (e.g., 20%) from the pre-calculated shortcut value: