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956.java
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956.java
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__________________________________________________________________________________________________
sample 6 ms submission
class Solution {
public int tallestBillboard(int[] A) {
int n = A.length;
if (n == 0) {
return 0;
}
int sum = 0;
for (int num : A) {
sum += num;
}
int[][] diff = new int[n][sum + 1];
// diff[i][j]: after adding in A[i], for height difference of j, the max height of the shorter support.
for (int i = 0; i < n; i++) {
for (int j = 0; j <= sum; j++) {
diff[i][j] = -1;
}
}
diff[0][0] = 0;
diff[0][A[0]] = 0;
for (int i = 1; i < n; i++) {
for (int j = 0; j <= sum; j++) {
if (diff[i - 1][j] == -1) {
continue;
}
//System.out.println(i + " " +j +" " + diff[i - 1][j]);
int d1 = j, d2 = j + A[i], d3 = Math.abs(j - A[i]);
diff[i][d1] = Math.max(diff[i][d1], diff[i - 1][j]);
diff[i][d2] = Math.max(diff[i][d2], diff[i - 1][j]);
diff[i][d3] = Math.max(diff[i][d3], diff[i - 1][j] + Math.min(j, A[i]));
}
}
return diff[n - 1][0];
}
}
__________________________________________________________________________________________________
sample 35588 kb submission
class Solution {
public int tallestBillboard(int[] rods) {
int sum = 0;
sum = Arrays.stream(rods).sum();
int n = rods.length;
//dp[i][j] - whether sum of first i nums can be (j-sum) - using offset of sum to avoid going in -ve
//dp[i + 1][j] = dp[i][j - rods[i]] | dp[i][j + rods[i]] | dp[i][j]
//max[i][j] represents the largest sum of all positive numbers when the sum of first i numbers is j - sum
boolean[][] dp = new boolean[n + 1][2*sum+1];
int[][] max = new int[n + 1][2*sum+1];
dp[0][sum] = true;
for (int i = 0; i < n; i++) {
for (int j = 0; j <= 2*sum; j++) {
if (j - rods[i] >= 0 && dp[i][j - rods[i]]) {
dp[i + 1][j] = true;
max[i + 1][j] = Math.max(max[i + 1][j], max[i][j - rods[i]] + rods[i]);
}
if (j + rods[i] <= 2*sum && dp[i][j + rods[i]]) {
dp[i + 1][j] = true;
max[i + 1][j] = Math.max(max[i + 1][j], max[i][j + rods[i]]);
}
if (dp[i][j]) {
dp[i + 1][j] = true;
max[i + 1][j] = Math.max(max[i + 1][j], max[i][j]);
}
}
}
return max[n][sum];
}
}
__________________________________________________________________________________________________