Add c smaller numbers algorithm

Author: Alex0Blackwell

Algorithms/smallerNumbersThanCurrent.c

@@ -0,0 +1,29 @@
+int cmpfunc(const void * a, const void * b) {
+   return ( *(int*)a - *(int*)b );
+}
+
+
+/**
+ * Note: The returned array must be malloced, assume caller calls free().
+ */
+int* smallerNumbersThanCurrent(int* nums, int numsSize, int* returnSize) {
+    int *res = malloc(sizeof(int) * numsSize);
+    *returnSize = numsSize;
+    
+    int * numsCpy = malloc(sizeof(int) * numsSize);
+    for(int i = 0; i < numsSize; ++i)
+        numsCpy[i] = nums[i];
+    
+    qsort(numsCpy, numsSize, sizeof(int), cmpfunc);
+    
+    for(int i = 0; i < numsSize; ++i) {
+        int ii = 0;
+        while(numsCpy[ii++] != nums[i]);
+        
+        res[i] = ii-1;
+    }
+    
+    free(numsCpy);
+    
+    return res;
+}

README.md

@@ -32,6 +32,8 @@ Click to expand the 9 *C programs*!
     - reverse an array in place
   - reverseStr.c
     - reverse string
+  - smallerNumbersThanCurrent
+    - Given the array nums, for each nums[i] find out how many numbers in the array are smaller than it.
   - squareCalc.c
     - return the square of a number with just addition
     - inductive assert