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Diffstat (limited to 'build_arr_permutation.c')
-rw-r--r-- | build_arr_permutation.c | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/build_arr_permutation.c b/build_arr_permutation.c new file mode 100644 index 0000000..379e989 --- /dev/null +++ b/build_arr_permutation.c @@ -0,0 +1,31 @@ +// 1920. Build Array from Permutation +#include "leetcode.h" + +/* + * given a 0-based permutation 'nums', build an array 'ans' of the same length + * where 'ans[i] = nums[nums[i]]' for each '0 <= i < nums.len' and return it. a + * 0-based permutation 'nums' is an array of distinct integers from 0 to + * 'nums.len - 1'. + */ + +int *buildArray(int *nums, int numsSize, int *returnSize) { + *returnSize = numsSize; + for (int i = 0; i < numsSize; i++) + nums[i] += (nums[nums[i]] & 1023) << 10; + for (int i = 0; i < numsSize; i++) + nums[i] >>= 10; + return nums; +} + +int main() { + int n1[] = {0, 2, 1, 5, 3, 4}, rs1; + int n2[] = {5, 0, 1, 2, 3, 4}, rs2; + int *ba1 = buildArray(n1, ARRAY_SIZE(n1), &rs1); + int *ba2 = buildArray(n2, ARRAY_SIZE(n2), &rs2); + for (int i = 0; i < rs1; i++) + printf("%d ", ba1[i]); // expect: 0 1 2 4 5 3 + printf("\n"); + for (int i = 0; i < rs2; i++) + printf("%d ", ba2[i]); // expect: 4 5 0 1 2 3 + printf("\n"); +} |