title
Given a non-empty array containing only positive integers, find if the array can be partitioned into two subsets such that the sum of elements in both subsets is equal.
Note:
- Each of the array element will not exceed 100.
- The array size will not exceed 200.
Example 1:
Input: [1, 5, 11, 5]
Output: true
Explanation: The array can be partitioned as [1, 5, 5] and [11].
Example 2:
Input: [1, 2, 3, 5]
Output: false
Explanation: The array cannot be partitioned into equal sum subsets.
solution
01背包，记得dp[0]=true;
class Solution {
public:
bool canPartition(vector<int>& nums) {
int psum = 0, sum = 0;
for (int num : nums) {
sum += num;
}
if (sum == 0 || sum % 2 == 1) {
return false;
}
psum = sum/2;
bool *dp = new bool[psum + 1];
fill(dp, dp + psum + 1, false);
dp[0]=true;
sort(nums.begin(), nums.end());
for (int num : nums) {
for (int i = psum; i >= 0; i--) {
if (i >= num) {
dp[i] = (dp[i] || dp[i - num]);
}
}
}
return dp[psum];
}
};