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// 63. Unique Paths II
#include "leetcode.h"

/*
  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.

  The testcases are generated so that the answer will be less than or equal to 2
  * 109.
 */

class Solution {
public:
  int uniquePathsWithObstacles(vector<vector<int>> &obstacleGrid) {
    int m = obstacleGrid.size(), n = obstacleGrid[0].size();
    vvd(int) dp(m + 1, vector<int>(n + 1, 0));
    dp[0][1] = 1;
    for (int i = 1; i <= m; ++i)
      for (int j = 1; j <= n; ++j)
        if (!obstacleGrid[i - 1][j - 1])
          dp[i][j] = dp[i - 1][j] + dp[i][j - 1];
    return dp[m][n];
  }
};

int main() {
  Solution obj;
  vvd(int) og1 = {{0, 0, 0}, {0, 1, 0}, {0, 0, 0}}, og2 = {{0, 1}, {0, 0}};
  printf("%d\n", obj.uniquePathsWithObstacles(og1)); // expect: 2
  printf("%d\n", obj.uniquePathsWithObstacles(og2)); // expect: 1
}