Create 1064-fixed-point.js

Author: everthis

1064-fixed-point.js

@@ -0,0 +1,15 @@
+/**
+ * @param {number[]} arr
+ * @return {number}
+ */
+const fixedPoint = function(arr) {
+  const n = arr.length
+  let l = 0, r = n - 1
+  while(l < r) {
+    const mid = l + ((r - l) >> 1)
+    if(arr[mid] < mid) l =  mid + 1
+    else if(arr[mid] > mid) r = mid - 1
+    else r = mid
+  }
+  return arr[l] === l ? l : -1
+};