A famous problem at the intersection of topology and combinatorial graph theory is the Utility Problem. Say you have three houses and three utilities and you need to connect each house to each utility ...

Given a non-empty binary tree, find the maximum path sum. For this problem, a path is defined as any sequence of nodes from some starting node to any node in the tree along the parent-child ...

Photos, left to right: After school program in Honduras, courtesy of Honduran Youth Alliance/Alianza Joven Honduras; U.S. Border Patrol Agent training Guatemalan Police, by Miguel Negronvia ...