Create 2125-number-of-laser-beams-in-a-bank.js

Author: everthis

2125-number-of-laser-beams-in-a-bank.js

@@ -0,0 +1,24 @@
+/**
+ * @param {string[]} bank
+ * @return {number}
+ */
+var numberOfBeams = function(bank) {
+  const comb = (num1, num2) => num1 * num2
+  const m = bank.length, n = bank[0].length
+  if(m === 0 || n === 0) return 0
+  let pre = 0, res = 0
+  for(let j = 0; j < n; j++) {
+    if(bank[0][j] === '1') pre++
+  }
+  for(let i = 1; i < m; i++) {
+    let chk = 0, cur = bank[i]
+    for(let j = 0; j < n; j++) {
+      if(cur[j] === '1') chk++
+    }
+    if(chk) {
+      res += comb(pre, chk)
+      pre = chk
+    }
+  }
+  return res
+};