404. Sum of Left Leaves
Find the sum of all left leaves in a given binary tree.
Example:
3
/ 9 20
/ 15 7
There are two left leaves in the binary tree, with values 9 and 15 respectively. Return 24.
package leetcode.easy;
/**
* Definition for a binary tree node. public class TreeNode { int val; TreeNode
* left; TreeNode right; TreeNode(int x) { val = x; } }
*/
public class SumOfLeftLeaves {
public int sumOfLeftLeaves(TreeNode root) {
if (null == root) {
return 0;
}
if (root.left != null && root.left.left == null && root.left.right == null) {
return root.left.val + sumOfLeftLeaves(root.right);
} else {
return sumOfLeftLeaves(root.left) + sumOfLeftLeaves(root.right);
}
}
@org.junit.Test
public void test() {
TreeNode tn11 = new TreeNode(3);
TreeNode tn21 = new TreeNode(9);
TreeNode tn22 = new TreeNode(20);
TreeNode tn33 = new TreeNode(15);
TreeNode tn34 = new TreeNode(7);
tn11.left = tn21;
tn11.right = tn22;
tn21.left = null;
tn21.right = null;
tn22.left = tn33;
tn22.right = tn34;
tn33.left = null;
tn33.right = null;
tn34.left = null;
tn34.right = null;
System.out.print(sumOfLeftLeaves(tn11));
}
}
LeetCode_404. Sum of Left Leaves
原文：https://www.cnblogs.com/denggelin/p/11910180.html