Create 1914-cyclically-rotating-a-gridsubmissions.js

Author: everthis

1914-cyclically-rotating-a-gridsubmissions.js

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+/**
+ * @param {number[][]} grid
+ * @param {number} k
+ * @return {number[][]}
+ */
+var rotateGrid = function(grid, k) {
+    var m = grid.length;
+    var n = grid[0].length;
+	
+	  // step1: loop each layer
+    var layer = Math.min(n/2, m/2);
+    for(l = 0; l<layer; l++) {
+	     // step2: flat layer "l" into one-dimension array
+        var cur = [];
+        // top
+        for(var j = l; j<n-l; j++)
+        {
+            cur.push(grid[l][j]);
+        }
+        // right
+        for(var i = l+1; i<m-l; i++)
+        {
+            cur.push(grid[i][n-l-1]);
+        }
+        // bottom
+        for(var j = n-l-2; j>=l; j--)
+        {
+            cur.push(grid[m-l-1][j]);
+        }
+        // left
+        for(var i = m-l-2; i>l; i--)
+        {
+            cur.push(grid[i][l]);
+        }
+		
+        // step3: rotation (k%len) on one-dimension array
+        var d = cur.length;
+        var offset = k % d;
+        cur = [...cur.slice(offset, d), ...cur.slice(0, offset)];
+		
+        // step4: refill rotated array back to 2D array at current layer
+        var index = 0;
+        // top
+        for(var j = l; j<n-l; j++)
+        {
+            grid[l][j] = cur[index++];
+        }
+        // right
+        for(var i = l+1; i<m-l; i++)
+        {
+            grid[i][n-l-1] = cur[index++];
+        }
+        // bottom
+        for(var j = n-l-2; j>=l; j--)
+        {
+            grid[m-l-1][j] = cur[index++];
+        }
+        // left
+        for(var i = m-l-2; i>l; i--)
+        { 
+            grid[i][l] = cur[index++];
+        }
+    }
+    return grid;
+};