// 1964. Find the Longest Valid Obstacle Course at Each Position #include "leetcode.h" /* * you want to build obstacle courses. you are given a 0-indexed integer array * 'obstacles' of length 'n' where 'obstacles[i]' describes the height of the * i'th obstacle. for every index 'i' between 0 and 'n - 1' (inclusive), find * the length of the longest obstacle course in 'obstacles' such that: * - you choose any number of obstacles between 0 and 'i' inclusive * - you must include the i'th obstacle in the course * - you must put the chosen obstacles in the same order as they appear in * 'obstacles' * - every obstacle (except the first) is taller than or the same height as the * obstacle immediately before it return an array 'ans' of length 'n', where * 'ans[i]' is the length of the longest obstacle course for index 'i' as * described aboveeeeeeeee */ class Solution { public: vector longestObstacleCourseAtEachEachPosition(vector &obstacles) { vector n; for (int i = 0; i < obstacles.size(); ++i) { auto it = upper_bound(n.begin(), n.end(), obstacles[i]); if (it == n.end()) { n.push_back(obstacles[i]); it = prev(n.end()); } else { *it = obstacles[i]; } obstacles[i] = it - n.begin() + 1; } return obstacles; } }; int main() { Solution obj; vector o1 = {1, 2, 3, 2}, o2 = {2, 2, 1}, o3 = {3, 1, 5, 6, 4, 2}; for (auto i : obj.longestObstacleCourseAtEachEachPosition(o1)) printf("%d ", i); // expect: 1 2 3 3 printf("\n"); for (auto i : obj.longestObstacleCourseAtEachEachPosition(o2)) printf("%d ", i); // expect: 1 2 1 printf("\n"); for (auto i : obj.longestObstacleCourseAtEachEachPosition(o3)) printf("%d ", i); // expect: 1 1 2 3 2 2 printf("\n"); }