Create 985-sum-of-even-numbers-after-queries.js

Author: everthis

985-sum-of-even-numbers-after-queries.js

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+/**
+ * @param {number[]} A
+ * @param {number[][]} queries
+ * @return {number[]}
+ */
+const sumEvenAfterQueries = function(A, queries) {
+  const res = []
+  for(let i = 0; i < queries.length; i++) {
+    A[queries[i][1]] += queries[i][0]
+    res.push(sum(A))
+  }
+  return res
+};
+
+function sum(arr) {
+  return arr.reduce((ac, el) => ac + (el % 2 === 0 ? el : 0), 0)
+}
+
+// another, better
+
+const sumEvenAfterQueries = function(A, queries) {
+    let sum = A.reduce((acc, cur) => cur%2 == 0 ? acc + cur : acc, 0);
+    return queries.map((q) => {
+        let i = q[1];
+        let s = A[i] + q[0];
+        if(s%2 === 0) {
+            sum += q[0];
+            if(A[i]%2 !== 0) sum += A[i];
+        } else if(A[i]%2 === 0) sum -= A[i];
+        A[i] = s;
+        return sum;
+    });
+};