一个牛有N堆牌，每堆排数量不等。一只牛一次可以将第i堆到第j堆各打一张出去，问最少几次打完

 

想通了很简单

#include<bits/stdc++.h>
using namespace std;
//input by bxd
#define rep(i,a,b) for(int i=(a);i<=(b);i++)
#define repp(i,a,b) for(int i=(a);i>=(b);--i)
#define RI(n) scanf("%d",&(n))
#define RII(n,m) scanf("%d%d",&n,&m)
#define RIII(n,m,k) scanf("%d%d%d",&n,&m,&k)
#define RS(s) scanf("%s",s);
#define ll long long
#define pb push_back
#define CLR(A,v)  memset(A,v,sizeof A)
//////////////////////////////////
#define inf 0x3f3f3f3f
#define lson l,m,pos<<1
#define rson m+1,r,pos<<1|1
const int N=1e5+6;
ll a[N],ans,n;

int main()
{
    RI(n);rep(i,1,n)cin>>(a[i]);
    rep(i,1,n)
    if(a[i]-a[i-1]>0)
    ans+=a[i]-a[i-1];
    cout<<ans;
    return 0;
}

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