Create 1964-find-the-longest-valid-obstacle-course-at-each-position.js

Author: everthis

1964-find-the-longest-valid-obstacle-course-at-each-position.js

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+/**
+ * @param {number[]} obstacles
+ * @return {number[]}
+ */
+const longestObstacleCourseAtEachPosition = function(obstacles) {
+  const n = obstacles.length
+  const stack = [], res = Array(n).fill(0)
+  let m = 0
+  let j = 0;
+  for (let x of obstacles) {
+    let i = chk(x);
+    if (i == m) {
+      ++m;
+      stack.push(x);
+    } else {
+      stack[i] = x;
+    }
+    res[j++] = i + 1;
+  }
+  return res;
+  function chk(x) {
+      if (m && stack[m - 1] <= x) return m;
+      let l = 0, r = m - 1;
+      while (l < r) {
+        let m = (l + r) >> 1;
+        if (stack[m] > x) {
+          r = m;
+        } else {
+          l = m + 1;
+        }
+      }
+      return l;
+  }
+};
+