[Codeforces] The Fibonacci Segment

http://codeforces.com/problemset/problem/365/B

最开始我寻思这题分治题吧, 就开始分, 感觉分治还是写的少控制的不好, 4wa, 都快放弃了,

后来群里halo大神说, 他用暴力解的O(n), 我顿悟了, 开始暴力裸写, 一次A掉.

思路就是:遍历数组, 用两个"指针", l和r, 来标识找到的斐波那契数列, 每找到新的 都记录一下len(l,r), 并更新l和r值.

#include <cstdio>
#include <vector>

using namespace std;

int arr[100001] = {0};
int num = 0;

int getLen(int left, int right) {
    return right - left + 1;
}
int solve() {
    if (num == 1 || num == 2) {
        return num;
    }
    int l = 0, r = 0, m = 0;
    for (int i = 0; i + 2 < num; ++i) {
        if (arr[i] + arr[i + 1] == arr[i + 2]) {
            r = i + 2;
        } else {
            if (getLen(l, i + 1) > m) {
                m = getLen(l, i + 1);
            } 
            l = i + 1;
        }
    }
    int t = getLen(l, r);
    if (t > m) {
        m = t;
    }
    return m;
}

int main()
{
    scanf("%d", &num);
    for (int i = 0; i < num; ++i) {
        scanf("%d", &arr[i]);
    }
    printf("%d\n", solve());
    return 0;
}