Add 1288 in c language

Author: julienChemillier

c/1288-Remove-Covered-Intervals.c

@@ -0,0 +1,34 @@
+/*
+Given an array intervals where intervals[i] = [li, ri] represent the interval
+[li, ri), remove all intervals that are covered by another interval in the list.
+Return the number of remaining intervals.
+
+Time: O(nlog(n)) (where n is the number of intervals)
+Space: O(1)
+*/
+
+int cmp_fun(const void *const_a, const void *const_b) {
+    const int* interval_a = *(const int **)const_a;
+    const int* interval_b = *(const int **)const_b;
+    if (interval_a[0] == interval_b[0])
+        return interval_b[1] - interval_a[1];
+    else
+        return interval_a[0] - interval_b[0];
+}
+
+int removeCoveredIntervals(int** intervals, int intervalsSize, int* intervalsColSize){
+    // Sorting of intervals: a<=b ⇔ ( a[0]<b[0] || (a[0]==b[0] && a[1]>b[1] )
+    qsort(intervals, intervalsSize, sizeof(int*), cmp_fun);
+
+    // Treatment of intervals sorted
+    int end = 0;
+    int number_remaining = intervalsSize;
+    for (int i=0; i<intervalsSize; i++) {
+        if (intervals[i][1]<=end) {
+            number_remaining--;
+        } else {
+            end = intervals[i][1];
+        }
+    }
+    return number_remaining;
+}