[leetcode]769. Max Chunks To Make Sorted

Analysis

ummmmmmm—— [ummmm~]

Given an array arr that is a permutation of [0, 1, …, arr.length - 1], we split the array into some number of “chunks” (partitions), and individually sort each chunk. After concatenating them, the result equals the sorted array.
What is the most number of chunks we could have made?
因为数组正确排序之后第i位上的数字应该是i，所以我们只要遍历数组，每次将最大的那个值标记为maxi，maxi必须在i处才能满足对0～i数字排序后能够恰好是正确的位置，此时res+1，表示前面的可以组为一个“块”，最后ans即为所求的值

Implement

class Solution {
public:
    int maxChunksToSorted(vector<int>& arr) {
        int len = arr.size();
        int res = 0;
        int maxi = INT_MIN;
        for(int i=0; i<len; i++){
            maxi = max(maxi, arr[i]);
            if(maxi == i)
                res++;
        }
        return res;
    }
};