LeetCode 785 Is Graph Bipartite? - Walkthrough

let's trace graph = [[1,3],[0,2],[1,3],[0,2]]. Start: color = [-1,-1,-1,-1]. Node $0$ is uncolored. BFS from $0$: color $0$ as $0$. Queue: [0]. Pop $0$. Neighbors: $1$, $3$. Both uncolored. Color $1$ as $1$, color $3$ as $1$. Queue: [1, 3]. Pop $1$. Neighbors: $0$, $2$. $0$ has color $0$ (opposite of $1$, good). $2$ uncolored.

Color $2$ as $0$. Queue: [3, 2]. Pop $3$. Neighbors: $0$, $2$. Both already colored correctly. Pop $2$. Neighbors: $1$, $3$. Both already colored correctly. No conflicts. Return true.