Update 2209-minimum-white-tiles-after-covering-with-carpets.js

Author: everthis

2209-minimum-white-tiles-after-covering-with-carpets.js

@@ -11,10 +11,15 @@ const minimumWhiteTiles = function(floor, numCarpets, carpetLen) {
   // when using j tiles to cover the first i tiles 
   const dp = Array.from({ length: n + 1 }, () => Array(numCarpets + 1).fill(0))
 
+  const ones = Array(n + 1).fill(0)
   for(let i = 1; i <= n; i++) {
-    for(let j = 0; j <= numCarpets; j++) {
+    ones[i] = ones[i - 1] + (floor[i - 1] === '1' ? 1 : 0) 
+  }
+  for(let i = 1; i <= n; i++) {
+    dp[i][0] = ones[i]
+    for(let j = 1; j <= numCarpets; j++) {
       const skip = dp[i - 1][j] + (floor[i - 1] === '1' ? 1 : 0)
-      const cover = j > 0 ? dp[Math.max(i - carpetLen, 0)][j - 1] : 1000
+      const cover = dp[Math.max(i - carpetLen, 0)][j - 1]
       dp[i][j] = Math.min(skip, cover)
     }
   }