uva 548 - Tree

利用中序和后序构建二叉树然后进行dfs搜索，两步可以同时进行，另外这道题目输入处理也有点麻烦，参考了一些大神的代码，自己重写因为一个值每次case之后未初始化悲剧的RE了好多次。

 

查了下 runtime error的可能大概有：

Runtime Error(ARRAY_BOUNDS_EXCEEDED) // array bounds exceed     数组越界
Runtime Error(DIVIDE_BY_ZERO) //divisor is nil                                   除零
Runtime Error(ACCESS_VIOLATION) //illegal memory access                  非法内存读取
Runtime Error(STACK_OVERFLOW) //stack overflow                             系统栈过载

 

 

#include<stdio.h>

int in[10010];
int post[10010];
int minSum;
int res;

int findIndex(int key, int*array, int n) {
	int i;
	for (i = 0; i < n; i++) {
		if (array[i] == key)
			return i;
	}
	return -1;
}

void dfs(int n, int*in, int*post, int sum) {
	if (n <= 0)
		return;
	int root = post[n - 1];
	if (n == 1) {
		int tmpSum = sum + root;
		if (tmpSum < minSum) {
			minSum = tmpSum;
			res = root;
		} else if (tmpSum == minSum)
			res = res < root ? res : root;
		return;
	}

	int index = findIndex(post[n - 1], in, n);
	dfs(index, in, post, sum + root);
	dfs(n - index - 1, in + index + 1, post + index, sum + root);

}

int main() {
	/*	setbuf(stdout,NULL);*/
	char ch;
	int i, n;

	while (scanf("%d%c", &in[0], &ch) != EOF) {
		minSum = 0x7fffffff;
		res = 0x7fffffff;
		if (ch == '\n') {
			scanf("%d", &post[0]);
			printf("%d\n", post[0]);
			continue;
		}
		n = 1;
		while (scanf("%d%c", &in[n++], &ch)) {
			if (ch == '\n')
				break;
		}

		for (i = 0; i < n; i++)
			scanf("%d", &post[i]);

		dfs(n, in, post, 0);
		printf("%d\n", res);

	}

	return 0;
}