I hate Shortest Path Problem

AtCoder

IDabc177_f

Time2000ms

Memory256MB

Difficulty—

There is a grid of squares with $H+1$ horizontal rows and $W$ vertical columns. You will start at one of the squares in the top row and repeat moving one square right or down. However, for each integer $i$ from $1$ through $H$, you cannot move down from the $A_i$\-th, $(A_i + 1)$\-th, $\ldots$, $B_i$\-th squares from the left in the $i$\-th row from the top. For each integer $k$ from $1$ through $H$, find the minimum number of moves needed to reach one of the squares in the $(k+1)$\-th row from the top. (The starting square can be chosen individually for each case.) If, starting from any square in the top row, none of the squares in the $(k+1)$\-th row can be reached, print `-1` instead. ## Constraints * $1 \leq H,W \leq 2\times 10^5$ * $1 \leq A_i \leq B_i \leq W$ ## Input Input is given from Standard Input in the following format: $H$ $W$ $A_1$ $B_1$ $A_2$ $B_2$ $:$ $A_H$ $B_H$ [samples]

Samples

Input #1

Output #1

1
3
6
-1

Let $(i,j)$ denote the square at the $i$\-th row from the top and $j$\-th column from the left.
For $k=1$, we need one move such as $(1,1)$ → $(2,1)$.
For $k=2$, we need three moves such as $(1,1)$ → $(2,1)$ → $(2,2)$ → $(3,2)$.
For $k=3$, we need six moves such as $(1,1)$ → $(2,1)$ → $(2,2)$ → $(3,2)$ → $(3,3)$ → $(3,4)$ → $(4,4)$.
For $k=4$, it is impossible to reach any square in the fifth row from the top.

API Response (JSON)

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Full JSON Raw Segments