[pull] master from youngyangyang04:master

problems/0063.不同路径II.md

@@ -382,8 +382,37 @@ var uniquePathsWithObstacles = function(obstacleGrid) {
 
     return dp[m - 1][n - 1]
 };
+
+// 版本二：内存优化，直接以原数组为dp数组
+var uniquePathsWithObstacles = function(obstacleGrid) {
+    const m = obstacleGrid.length;
+    const n = obstacleGrid[0].length;
+    for (let i = 0; i < m; i++) {
+        for (let j = 0; j < n; j++) {
+            if (obstacleGrid[i][j] === 0) {
+                // 不是障碍物
+                if (i === 0) {
+                    // 取左边的值
+                    obstacleGrid[i][j] = obstacleGrid[i][j - 1] ?? 1;
+                } else if (j === 0) {
+                    // 取上边的值
+                    obstacleGrid[i][j] = obstacleGrid[i - 1]?.[j] ?? 1;
+                } else {
+                    // 取左边和上边的和
+                    obstacleGrid[i][j] = obstacleGrid[i - 1][j] + obstacleGrid[i][j - 1];
+                }
+            } else {
+                // 如果是障碍物，则路径为0
+                obstacleGrid[i][j] = 0;
+            }
+        }
+    }
+    return obstacleGrid[m - 1][n - 1];
+};
 ```
 
+
+
 ### TypeScript
 
 ```typescript