You are given an m x n integer array grid. There is a robot initially located at the top-left corner (i.e., grid[0][0]). The robot tries to move to the bottom-right corner (i.e., grid[m-1][n-1]). The robot can only move either down or right at any point in time.
An obstacle and space are marked as 1 or 0 respectively in grid. A path that the robot takes cannot include any square that is an obstacle.
Return the number of possible unique paths that the robot can take to reach the bottom-right corner.
\n\nThe testcases are generated so that the answer will be less than or equal to 2 * 109.
\n
Example 1:
\n![\"\"](\"https://assets.leetcode.com/uploads/2020/11/04/robot1.jpg\")
\n\nInput: obstacleGrid = [[0,0,0],[0,1,0],[0,0,0]]\nOutput: 2\nExplanation: There is one obstacle in the middle of the 3x3 grid above.\nThere are two ways to reach the bottom-right corner:\n1. Right -> Right -> Down -> Down\n2. Down -> Down -> Right -> Right\n\n\n
Example 2:
\n![\"\"](\"https://assets.leetcode.com/uploads/2020/11/04/robot2.jpg\")
\n\nInput: obstacleGrid = [[0,1],[0,0]]\nOutput: 1\n\n\n
\n
Constraints:
\n\nm == obstacleGrid.lengthn == obstacleGrid[i].length1 <= m, n <= 100obstacleGrid[i][j] is 0 or 1.\r\nif obstacleGrid[i][j] is not an obstacle\r\n obstacleGrid[i,j] = obstacleGrid[i,j - 1] \r\nelse\r\n obstacleGrid[i,j] = 0\r\n\r\n\r\nYou can do a similar processing for finding out the number of ways of reaching the cells in the first column.", "For any other cell, we can find out the number of ways of reaching it, by making use of the number of ways of reaching the cell directly above it and the cell to the left of it in the grid. This is because these are the only two directions from which the robot can come to the current cell.", "Since we are making use of pre-computed values along the iteration, this becomes a dynamic programming problem.\r\n\r\n
\r\nif obstacleGrid[i][j] is not an obstacle\r\n obstacleGrid[i,j] = obstacleGrid[i,j - 1] + obstacleGrid[i - 1][j]\r\nelse\r\n obstacleGrid[i,j] = 0\r\n\r\n\r\n" ], "solution": { "id": "597", "canSeeDetail": true, "paidOnly": false, "hasVideoSolution": false, "paidOnlyVideo": true, "__typename": "ArticleNode" }, "status": null, "sampleTestCase": "[[0,0,0],[0,1,0],[0,0,0]]", "metaData": "{\r\n \"name\": \"uniquePathsWithObstacles\",\r\n \"params\": [\r\n {\r\n \"name\": \"obstacleGrid\",\r\n \"type\": \"integer[][]\"\r\n }\r\n ],\r\n \"return\": {\r\n \"type\": \"integer\"\r\n }\r\n}", "judgerAvailable": true, "judgeType": "large", "mysqlSchemas": [], "enableRunCode": true, "enableTestMode": false, "enableDebugger": true, "envInfo": "{\"cpp\": [\"C++\", \"
Compiled with clang 11 using the latest C++ 17 standard.
Your code is compiled with level two optimization (-O2). AddressSanitizer is also enabled to help detect out-of-bounds and use-after-free bugs.
Most standard library headers are already included automatically for your convenience.
\"], \"java\": [\"Java\", \" OpenJDK 17 . Java 8 features such as lambda expressions and stream API can be used.
Most standard library headers are already included automatically for your convenience.
\\r\\nIncludes Pair class from https://docs.oracle.com/javase/8/javafx/api/javafx/util/Pair.html.
Python 2.7.12.
Most libraries are already imported automatically for your convenience, such as array, bisect, collections. If you need more libraries, you can import it yourself.
\\r\\n\\r\\nFor Map/TreeMap data structure, you may use sortedcontainers library.
\\r\\n\\r\\nNote that Python 2.7 will not be maintained past 2020. For the latest Python, please choose Python3 instead.
\"], \"c\": [\"C\", \"Compiled with gcc 8.2 using the gnu99 standard.
Your code is compiled with level one optimization (-O1). AddressSanitizer is also enabled to help detect out-of-bounds and use-after-free bugs.
Most standard library headers are already included automatically for your convenience.
\\r\\n\\r\\nFor hash table operations, you may use uthash. \\\"uthash.h\\\" is included by default. Below are some examples:
\\r\\n\\r\\n1. Adding an item to a hash.\\r\\n
\\r\\nstruct hash_entry {\\r\\n int id; /* we'll use this field as the key */\\r\\n char name[10];\\r\\n UT_hash_handle hh; /* makes this structure hashable */\\r\\n};\\r\\n\\r\\nstruct hash_entry *users = NULL;\\r\\n\\r\\nvoid add_user(struct hash_entry *s) {\\r\\n HASH_ADD_INT(users, id, s);\\r\\n}\\r\\n\\r\\n\\r\\n\\r\\n2. Looking up an item in a hash:\\r\\n
\\r\\nstruct hash_entry *find_user(int user_id) {\\r\\n struct hash_entry *s;\\r\\n HASH_FIND_INT(users, &user_id, s);\\r\\n return s;\\r\\n}\\r\\n\\r\\n\\r\\n\\r\\n3. Deleting an item in a hash:\\r\\n
\\r\\nvoid delete_user(struct hash_entry *user) {\\r\\n HASH_DEL(users, user); \\r\\n}\\r\\n\\r\\n\"], \"csharp\": [\"C#\", \"\\r\\n\\r\\nYour code is compiled with debug flag enabled (/debug).
Node.js 16.13.2.
Your code is run with --harmony flag, enabling new ES6 features.
lodash.js library is included by default.
\\r\\n\\r\\nFor Priority Queue / Queue data structures, you may use datastructures-js/priority-queue and datastructures-js/queue.
\"], \"ruby\": [\"Ruby\", \"Ruby 3.1
Some common data structure implementations are provided in the Algorithms module: https://www.rubydoc.info/github/kanwei/algorithms/Algorithms
\"], \"swift\": [\"Swift\", \"Swift 5.5.2.
Go 1.17.6.
Support https://godoc.org/github.com/emirpasic/gods library.
\"], \"python3\": [\"Python3\", \"Python 3.10.
Most libraries are already imported automatically for your convenience, such as array, bisect, collections. If you need more libraries, you can import it yourself.
\\r\\n\\r\\nFor Map/TreeMap data structure, you may use sortedcontainers library.
\"], \"scala\": [\"Scala\", \"Scala 2.13.7.
Kotlin 1.3.10.
Rust 1.58.1
Supports rand v0.6\\u00a0from crates.io
\"], \"php\": [\"PHP\", \"PHP 8.1.
With bcmath module
\"], \"typescript\": [\"Typescript\", \"TypeScript 4.5.4, Node.js 16.13.2.
Your code is run with --harmony flag, enabling new ES2020 features.
lodash.js library is included by default.
\"], \"racket\": [\"Racket\", \"Run with Racket 8.3.