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// 2099. Find Subsequence of Length K With the Largest Sum
#include "leetcode.h"
/*
* you are given an integer array 'nums' and an integer 'k'. you want to find a
* subsequence of 'nums' of length 'k' that has the largest sum. return any such
* subsequence as an integer array of length 'k'. a subsequence is an array that
* can be derived from another array by deleting some or no elements without
* changing the order of the remaining elements.
*/
struct pair {
int idx;
int val;
};
int cmp_idx(const void *a, const void *b) {
struct pair aa = *(const struct pair *)a;
struct pair bb = *(const struct pair *)b;
return aa.idx - bb.idx;
}
int cmp_val(const void *a, const void *b) {
struct pair aa = *(const struct pair *)a;
struct pair bb = *(const struct pair *)b;
return aa.val - bb.val;
}
int *maxSubsequence(int *nums, int numsSize, int k, int *returnSize) {
struct pair *pairs = (struct pair *)malloc(numsSize * sizeof(struct pair));
for (int i = 0; i < numsSize; i++) {
pairs[i].idx = i;
pairs[i].val = nums[i];
}
qsort(pairs, numsSize, sizeof(struct pair), cmp_val);
qsort(pairs, k, sizeof(struct pair), cmp_idx);
int *ans = (int *)malloc(k * sizeof(int));
*returnSize = k;
for (int i = 0; i < k; i++)
ans[i] = nums[pairs[i].idx];
free(pairs);
return ans;
}
int main() {
int n1[] = {2, 1, 3, 3}, n2[] = {-1, -2, 3, 4}, n3[] = {3, 4, 3, 3};
int rs1, *ms1 = maxSubsequence(n1, ARRAY_SIZE(n1), 2, &rs1);
int rs2, *ms2 = maxSubsequence(n2, ARRAY_SIZE(n2), 3, &rs2);
int rs3, *ms3 = maxSubsequence(n3, ARRAY_SIZE(n3), 2, &rs3);
for (int i = 0; i < rs1; i++)
printf("%d ", ms1[i]); // expect: 3 3
printf("\n");
for (int i = 0; i < rs2; i++)
printf("%d ", ms2[i]); // expect: -1 3 4
printf("\n");
for (int i = 0; i < rs3; i++)
printf("%d ", ms3[i]); // expect: 3 4
printf("\n");
free(ms1);
free(ms2);
free(ms3);
}
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