totalTime to 0.left and right to 0.colors string using the right pointer.
a. For each group of balloons with the same color, calculate currTotal (sum of neededTime for the group) and currMax (maximum neededTime in the group).
b. Increment right until the color of the balloon at right is different from that at left.currTotal - currMax to totalTime.left to the current right to start processing the next group.colors string is reached.totalTime.