测试点2、3、5没过问题:网上调查之后发现,用float计算结果精度不够,改成double就好了
测试点6一开始超时了,当时代码:
#include<iostream>
#include<math.h>
#include<vector>
using namespace std;
vector<int>father;
vector <int> is_retailer;
int times;double sum;
double price, rate;
void dps(int end,int now) {
if (father[now] == -1) {
sum += is_retailer[end] * price * pow(1 + rate / 100, times);
return;
}
times++;
dps(end, father[now]);
}
int main() {
int N; cin >> N;
cin >> price >> rate;
father.resize(N,-1);
is_retailer.resize(N,-1);
for (int i = 0; i < N; i++) {
int number; cin >> number;
for (int j = 1; j <= number; j++) {
int child; cin >> child;
father[child] = i;
}
if (number == 0) cin >> is_retailer[i];
}
sum = 0;
for (int i = 0; i < N; i++) {
if (is_retailer[i] != -1) {
times = 0;
dps(i, i);
}
}
printf("%.1lf", sum);
return 0;
}
然后稍微看了一下这个链接的思路:PAT甲级1079_湛蓝的天空-CSDN博客
AC代码如下:
#include<iostream>
#include<math.h>
#include<vector>
using namespace std;
vector<int>children;
vector <int> is_retailer;
vector<int>layer;
double sum,price, rate;
void update(int father) {
if(children[father]==-1) return;
layer[children[father]] = layer[father] + 1;
update(children[father]);
}
int main() {
int N; cin >> N;
cin >> price >> rate;
children.resize(N,-1);
is_retailer.resize(N,-1);
layer.resize(N, 0);
for (int i = 0; i < N; i++) {
int number; cin >> number;
for (int j = 1; j <= number; j++) {
int child; cin >> child;
children[i] = child;
layer[child] = layer[i] + 1;
update(child);
}
if (number == 0) cin >> is_retailer[i];
}
sum = 0;
for (int i = 0; i < N; i++) {
if (is_retailer[i] != -1)
sum += is_retailer[i] * price * pow(1 + rate / 100, layer[i]);
}
printf("%.1lf", sum);
return 0;
}
相比改之前的代码,dps更新层数走过的路径更短,而改之前要把所有路走到头。