659. Split Array into Consecutive Subsequences

You are given an integer array sorted in ascending order (may contain duplicates), you need to split them into several subsequences, where each subsequences consist of at least 3 consecutive integers. Return whether you can make such a split.

Example 1:

Input: [1,2,3,3,4,5]Output: TrueExplanation:You can split them into two consecutive subsequences : 1, 2, 33, 4, 5

Example 2:

Input: [1,2,3,3,4,4,5,5]Output: TrueExplanation:You can split them into two consecutive subsequences : 1, 2, 3, 4, 53, 4, 5

Example 3:

Input: [1,2,3,4,4,5]Output: False

Note:

1. The length of the input is in range of [1, 10000]

分析

维护若干个队列，新插入的元素必须等于队尾元素+1。若找不到这样的队列，新创建一个队列，把 新元素放入。待所有元素都放入后，看是否所有队列的长度都不小于3.

code

#include <iostream>#include <vector>using namespace std;class Solution {public:    bool isPossible(vector<int>& nums) {        vector<vector<int> > v;        v.push_back(vector<int>());        v[0].push_back(nums[0]);        for (int i = 1; i < nums.size(); ++i) {        int flag=0;        for (int j = v.size()-1; j >= 0; --j) {        if (nums[i]==v[j].back()+1) {        v[j].push_back(nums[i]);        flag=1;        break;        }        }        if (flag==0) {        v.push_back(vector<int>());        v.back().push_back(nums[i]);        }        }        for (int i = 0; i < v.size(); ++i)        if (v[i].size() < 3) return false;        return true;    }};int main(int argc, char const *argv[]){int a[]={1,2,3,3,4,5};vector<int> nums(a,a+6);Solution s;cout << s.isPossible(nums);return 0;}