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-rw-r--r--add_arr_form_int.c42
1 files changed, 42 insertions, 0 deletions
diff --git a/add_arr_form_int.c b/add_arr_form_int.c
new file mode 100644
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--- /dev/null
+++ b/add_arr_form_int.c
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+// 989. Add to Array-Form of Integer
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+/*
+ * the array-form of an integer 'num' is an array representing its digits in
+ * left to right order. eg 'num = 1231', the array form is 1,3,2,1. given 'num',
+ * the array form of an integer, and an integer 'k', return the array-form of
+ * 'num + k'
+ */
+
+int *addToArrayForm(int *num, int numSize, int k, int *returnSize) {
+ int *k_arr, *ans, k_size, r_size, p;
+ for (int i = k, k_size = 0; i > 0; i /= 10)
+ k_size++;
+ k_arr = malloc(sizeof(int) * k_size);
+ for (int i = k_size - 1, p = k; i >= 0; p /= 10)
+ k_arr[i--] = p % 10;
+ r_size = k_size > numSize ? k_size : numSize;
+ ans = malloc(sizeof(int) * (++r_size));
+ for (int i = numSize, j = k_size, c = 0, p = r_size - 1; p >= 0; p--) {
+ c += i > 0 ? num[--i] : 0;
+ c += j > 0 ? k_arr[--j] : 0;
+ ans[p] = c % 10;
+ c /= 10;
+ }
+ if (ans[0] == 0)
+ memmove(ans, ans + 1, sizeof(int) * (--r_size));
+ *returnSize = r_size;
+ free(k_arr);
+ return ans;
+}
+
+int main() {
+ int num1[] = {1, 2, 0, 0}, ns1 = 4, k1 = 34, rs1[] = {4};
+ int num2[] = {2, 7, 4}, ns2 = 3, k2 = 181, rs2[] = {3};
+ int num3[] = {2, 1, 4}, ns3 = 3, k3 = 806, rs3[] = {4};
+ printf("%d\n" * addToArrayForm(num1, ns1, k1, rs1));
+ printf("%d\n" * addToArrayForm(num2, ns2, k2, rs2));
+ printf("%d\n" * addToArrayForm(num3, ns3, k3, rs3));
+}