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

Author: mdmzfzl

Diff for: c/1964-find-the-longest-valid-obstacle-course-at-each-position.c

@@ -0,0 +1,36 @@
+int upperBound(int *arr, int size, int target) {
+    int left = 0, right = size - 1;
+    while (left <= right) {
+        int mid = left + (right - left) / 2;
+        if (arr[mid] <= target) {
+            left = mid + 1;
+        } else {
+            right = mid - 1;
+        }
+    }
+    return left;
+}
+
+int* longestObstacleCourseAtEachPosition(int* obstacles, int obstaclesSize, int* returnSize) {
+    int* lis = (int*)malloc(obstaclesSize * sizeof(int));
+    int* result = (int*)malloc(obstaclesSize * sizeof(int));
+    *returnSize = obstaclesSize;
+
+    int lisSize = 0;
+
+    for (int i = 0; i < obstaclesSize; ++i) {
+        int x = obstacles[i];
+        if (lisSize == 0 || lis[lisSize - 1] <= x) {
+            lis[lisSize] = x;
+            result[i] = lisSize + 1;
+            lisSize++;
+        } else {
+            int idx = upperBound(lis, lisSize, x);
+            lis[idx] = x;
+            result[i] = idx + 1;
+        }
+    }
+
+    free(lis);
+    return result;
+}