add 3354

Author: clingoram

javascript/LeetCode/Array/3354.js

@@ -0,0 +1,48 @@
+/**
+ * 3354. Make Array Elements Equal to Zero
+ * 
+ * curr = index,nums[index] == 0
+ * 若curr超過範圍[0,nums.length - 1] 操作結束
+ * 若nums[index] == 0，則curr 增加（往右)，反之則curr減少（往左）
+ * nums[index] > 0 ，nums[current] - 1且左右反轉
+ * 
+ * @param {number[]} nums
+ * @return {number}
+ */
+var countValidSelections = function(nums) {
+    // you need to find the sum of all the numbers to the left of where nums[i]==0 and the sum of all the numbers to the right of that point. 
+    // If you need more help, look at the detailed explanation in this comment.
+    let ans = 0;
+    let sum = nums.reduce((a,b) => a + b,0);
+    let left = 0,right = sum;
+    for(let i = 0;i < nums.length;++i) {
+      if(nums[i] === 0){
+        if(left - right >= 0 && left - right <= 1) {
+          ans++;
+        }
+        if(right - left >= 0 && right - left <= 1) {
+          ans++;
+        }
+      }else{
+        left += nums[i];
+        right -= nums[i];
+      }
+    }
+    return ans;
+};
+let nums = [1,0,2,0,3];
+/**
+ * 2
+ * The only possible valid selections are the following:
+Choose curr = 3, and a movement direction to the left.
+[1,0,2,0,3] -> [1,0,2,0,3] -> [1,0,1,0,3] -> [1,0,1,0,3] -> [1,0,1,0,2] -> 
+[1,0,1,0,2] -> [1,0,0,0,2] -> [1,0,0,0,2] -> [1,0,0,0,1] -> [1,0,0,0,1] -> 
+[1,0,0,0,1] -> [1,0,0,0,1] -> [0,0,0,0,1] -> [0,0,0,0,1] -> [0,0,0,0,1] -> 
+[0,0,0,0,1] -> [0,0,0,0,0].
+
+Choose curr = 3, and a movement direction to the right.
+[1,0,2,0,3] -> [1,0,2,0,3] -> [1,0,2,0,2] -> [1,0,2,0,2] -> [1,0,1,0,2] -> 
+[1,0,1,0,2] -> [1,0,1,0,1] -> [1,0,1,0,1] -> [1,0,0,0,1] -> [1,0,0,0,1] -> 
+[1,0,0,0,0] -> [1,0,0,0,0] -> [1,0,0,0,0] -> [1,0,0,0,0] -> [0,0,0,0,0].
+ */
+console.log(countValidSelections(nums));