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// 416. Partition Equal Subset Sum
#include "leetcode.h"
/*
* given an integer array 'nums', return true if you can partition the array
* into two subsets such that the sum of the elements in both subsets is equal
* or false otherwise
*/
bool memo(int *nums, int **dp, int sum, int idx, int n) {
if (!sum)
return true;
if (idx >= n)
return false;
if (dp[idx][sum] != -1)
return dp[idx][sum];
bool pick = false, no_pick = false;
if (nums[idx] <= sum)
pick = memo(nums, dp, sum - nums[idx], idx + 1, n);
no_pick = memo(nums, dp, sum, idx + 1, n);
return dp[idx][sum] = (pick || no_pick);
}
bool canPartition(int *nums, int numsSize) {
int sum = 0;
for (int i = 0; i < numsSize; i++)
sum += nums[i];
if (sum & 1)
return false;
int **dp = (int **)malloc(numsSize * sizeof(int *));
for (int i = 0; i < numsSize; i++) {
dp[i] = (int *)malloc(((sum >> 1) + 1) * sizeof(int));
for (int j = 0; j < ((sum >> 1) + 1); ++j)
dp[i][j] = -1;
}
bool ans = memo(nums, dp, sum >> 1, 0, numsSize);
for (int i = 0; i < numsSize; i++)
free(dp[i]);
free(dp);
return ans;
}
int main() {
int n1[] = {1, 5, 11, 5}, n2[] = {1, 2, 3, 5};
printf("%d\n", canPartition(n1, ARRAY_SIZE(n1))); // expect: 1
printf("%d\n", canPartition(n2, ARRAY_SIZE(n2))); // expect: 0
}
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