class Solution {
public:
int integerBreak(int n) {
// dp[i] means output when input = i, e.g. dp[4] = 4 (2*2),dp[8] = 18 (2*3*3)...
vector<int> dp(n + 1, 0);
dp[1] = 1;
// fill the entire dp array
for(int i = 2; i <= n; i++) {
//let's say i = 8, we are trying to fill dp[8]:if 8 can only be broken into 2 parts, the answer could be among 1 * 7, 2 * 6, 3 * 5, 4 * 4... but these numbers can be further broken. "so we have to compare 1 with dp[1], 7 with dp[7], 2 with dp[2], 6 with dp[6]...etc"
for(int j = 1; j < i; j++) {
// use max(dp[i],....) so dp[i] maintain the greatest value
dp[i] = max(dp[i], (max(j, dp[j])) * (max(i - j, dp[i - j])));
}
}
return dp[n];
}
};