标签：style http color os io for ar div amp
There are N children standing in a line. Each child is assigned a rating value.
You are giving candies to these children subjected to the following requirements:
What is the minimum candies you must give?
题目说N个孩子排成一行，每个孩子被赋予一个rating，要求给candy给孩子满足每个孩子都至少有一个candy同时拥有更高rating
的孩子比他的邻居有更多的candy。
思路1：转为有向图，用拓扑排序。
拓扑排序用到了每个节点的入度（有多少个节点指向该节点）、从该节点出发直接到达的节点。
步骤：
class Solution {
public:
int candy(vector<int> &ratings) {
size_t len = ratings.size();
if (len == 1) {
return 1;
}
vector<int> ins(len, 0);
vector<vector<int> > outs(len, vector<int>());
for (int i = 0; i < len; ++i) {
if (i - 1 >= 0 && ratings[i - 1] > ratings[i]) {
++ins[i - 1];
outs[i].push_back(i - 1);
}
if (i + 1 < len && ratings[i + 1] > ratings[i]) {
++ins[i + 1];
outs[i].push_back(i + 1);
}
}
queue<pair<int, int> > q;
for (int i = 0; i < len; ++i) {
if (!ins[i]) {
q.push(make_pair(i, 1));
}
}
int ans = 0;
while (!q.empty()) {
pair<int, int> front = q.front();
q.pop();
ans += front.second;
for (int i = 0; i < outs[front.first].size(); ++i) {
--ins[outs[front.first][i]];
if (!ins[outs[front.first][i]]) {
q.push(make_pair(outs[front.first][i], front.second + 1));
}
}
}
return ans;
}
};class Solution {
public:
int candy(vector<int> &ratings) {
size_t len = ratings.size();
if (len == 1) {
return 1;
}
vector<int> candy_num(len, 0);
int ans = 0;
for (size_t i = 0; i < len; ++i) {
ans += get_candy_num(candy_num, i, len, ratings);
}
return ans;
}
private:
int get_candy_num(vector<int> &candy_num, size_t k, size_t len, vector<int> &ratings) {
if (candy_num[k]) return candy_num[k];
if (k == 0) {
if (ratings[k + 1] >= ratings[k]) {
return candy_num[k] = 1;
} else {
return candy_num[k] = get_candy_num(candy_num, k + 1, len, ratings) + 1;
}
} else if (k == len - 1) {
if (ratings[k - 1] >= ratings[k]) {
return candy_num[k] = 1;
} else {
return candy_num[k] = get_candy_num(candy_num, k - 1, len, ratings) + 1;
}
} else {
if (ratings[k - 1] >= ratings[k] && ratings[k + 1] >= ratings[k]) {
return candy_num[k] = 1;
} else if (ratings[k] > ratings[k - 1] && ratings[k] > ratings[k + 1]) {
int left = get_candy_num(candy_num, k - 1, len, ratings);
int right = get_candy_num(candy_num, k + 1, len, ratings);
left < right ? candy_num[k] = right + 1 : candy_num[k] = left + 1;
return candy_num[k];
} else if (ratings[k] > ratings[k - 1]) {
return candy_num[k] = get_candy_num(candy_num, k - 1, len, ratings) + 1;
} else if (ratings[k] > ratings[k + 1]) {
return candy_num[k] = get_candy_num(candy_num, k + 1, len, ratings) + 1;
}
}
return 1;
}
};标签：style http color os io for ar div amp
原文地址：http://blog.csdn.net/freeliao/article/details/38796747
