Can anyone give me the main idea to solve [APIO 2012 Problem 2 Guard](https://dmoj.ca/problem/apio12p2)?↵
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It is clear that when a guard reported 1 in a range **A**, then some guards reported 0 in every position in range **A** except position **I**. we are certain that there is a ninja at position **I**.↵
After calculating all positions that way(let's say we have found **IS** such positions), we still have **K-IS** ningas and that information can help us be certain about other positions, but I didn't know how to solve this problem in less than _**O(n²)**_.
↵
It is clear that when a guard reported 1 in a range **A**, then some guards reported 0 in every position in range **A** except position **I**. we are certain that there is a ninja at position **I**.↵
After calculating all positions that way(let's say we have found **IS** such positions), we still have **K-IS** ningas and that information can help us be certain about other positions, but I didn't know how to solve this problem in less than _**O(n²)**_.
