Create: 0056-merge-intervals.c

Author: mdmzfzl

c/0056-merge-intervals.c

@@ -0,0 +1,61 @@
+// Interval structure
+struct Interval {
+    int start;
+    int end;
+};
+
+// Function to compare intervals for sorting
+int compareIntervals(const void* a, const void* b) {
+    return ((struct Interval*)a)->start - ((struct Interval*)b)->start;
+}
+
+// Function to merge intervals
+int** merge(int** intervals, int intervalsSize, int* intervalsColSize, int* returnSize, int** returnColumnSizes) {
+    if (intervalsSize <= 1) {
+        *returnSize = intervalsSize;
+        *returnColumnSizes = intervalsColSize;
+        return intervals;
+    }
+
+    // Create an array of Interval structures
+    struct Interval* sortedIntervals = (struct Interval*)malloc(sizeof(struct Interval) * intervalsSize);
+    for (int i = 0; i < intervalsSize; i++) {
+        sortedIntervals[i].start = intervals[i][0];
+        sortedIntervals[i].end = intervals[i][1];
+    }
+
+    // Sort intervals based on start times
+    qsort(sortedIntervals, intervalsSize, sizeof(struct Interval), compareIntervals);
+
+    // Merge intervals
+    struct Interval* mergedIntervals = (struct Interval*)malloc(sizeof(struct Interval) * intervalsSize);
+    int mergedCount = 0;
+
+    for (int i = 0; i < intervalsSize; i++) {
+        if (mergedCount == 0 || mergedIntervals[mergedCount - 1].end < sortedIntervals[i].start) {
+            mergedIntervals[mergedCount++] = sortedIntervals[i];
+        } else {
+            mergedIntervals[mergedCount - 1].end = mergedIntervals[mergedCount - 1].end > sortedIntervals[i].end
+                                                      ? mergedIntervals[mergedCount - 1].end
+                                                      : sortedIntervals[i].end;
+        }
+    }
+
+    // Allocate memory for return arrays
+    int** result = (int**)malloc(sizeof(int*) * mergedCount);
+    *returnColumnSizes = (int*)malloc(sizeof(int) * mergedCount);
+
+    for (int i = 0; i < mergedCount; i++) {
+        result[i] = (int*)malloc(sizeof(int) * 2);
+        result[i][0] = mergedIntervals[i].start;
+        result[i][1] = mergedIntervals[i].end;
+        (*returnColumnSizes)[i] = 2;
+    }
+
+    *returnSize = mergedCount;
+
+    free(sortedIntervals);
+    free(mergedIntervals);
+
+    return result;
+}