901. 股票价格跨度
kmp的next数组的思想
next[i]表示第i个数左边,第一个比第i个数大的数的下标
vector里对每个数存储其连续字段和price
如果当前的price比前一个数大,则返回1
否则往前遍历next,每次都加v[next[i]].cnt,直到next[i] == -1 或者 v[next[i]].price > price
class StockSpanner { public: struct node{ int price, cnt; node(int price, int cnt):price(price), cnt(cnt){} }; vector<node> v; int pre[150010]; StockSpanner() { } int next(int price) { int cnt = 1; int i = v.size(); if(i - 1 == -1) { v.push_back(node(price, cnt)); pre[i] = -1; } else if(v[i - 1].price > price) { v.push_back(node(price, cnt)); pre[i] = i - 1; } else { int k = i - 1; while(k != -1 && v[k].price <= price) { cnt += v[k].cnt; k = pre[k]; } pre[i] = k; v.push_back(node(price, cnt)); } return cnt; } }; /** * Your StockSpanner object will be instantiated and called as such: * StockSpanner* obj = new StockSpanner(); * int param_1 = obj->next(price); */
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