CodeTON Round 7 (Div. 1 + Div. 2, Rated, Prizes!) D. Ones and Twos

Codeforces Round 908 (Div. 1) B. Neutral Tonality

Codeforces Round 906 (Div. 1) B. Doremy’s Connecting Plan

Educational Codeforces Round 156 (Rated for Div. 2) C. Decreasing String

Codeforces Round 904 (Div. 2) C. Medium Design

3119. Maximum Number of Potholes That Can Be Fixed

You are given a string road, consisting only of characters "x" and ".", where each "x" denotes a pothole and each "." denotes a smooth road, and an integer budget.

In one repair operation, you can repair n consecutive potholes for a price of n + 1.

Return the maximum number of potholes that can be fixed such that the sum of the prices of all of the fixes doesn’t go over the given budget.

3109. Find the Index of Permutation

Given an array perm of length n which is a permutation of [1, 2, ..., n], return the index of perm in the lexicographically sorted array of all of the permutations of [1, 2, ..., n].

Since the answer may be very large, return it modulo 109 + 7.

463. Island Perimeter

You are given row x col grid representing a map where grid[i][j] = 1 represents land and grid[i][j] = 0 represents water.

grid is completely surrounded by water, and there is exactly one island (i.e., one or more connected land cells).

The island doesn’t have “lakes”, meaning the water inside isn’t connected to the water around the island. One cell is a square with side length 1. The grid is rectangular, width and height don’t exceed 100. Determine the perimeter of the island.

Codeforces Round 905 (Div. 3) E. Look Back

Codeforces Round 903 (Div. 3) F. Minimum Maximum Distance