1329A - Dreamoon Likes Coloring - CodeForces Solution

#include<cstdio>
#include<algorithm>
using namespace std;
int a[100005],b[100005];
int main(){
	int n,m,i;
	long long sum=0;
	scanf("%d%d",&n,&m);
	b[m+1]=2147483647; 
	for(i=1;i<=m;i++){
		scanf("%d",&a[i]);
		sum+=a[i];
		if(a[i]+i>n+1){
			printf("-1");
			return 0;
		}
	}
	if(sum<n){
		printf("-1");
		return 0;
	}
	for(i=m;i;i--){
		b[i]=min(n-a[i]+1,b[i+1]-1);
	}
	b[1]=1;
	for(i=2;i<=m;i++){
		if(b[i-1]+a[i-1]>=b[i]){
			break;
		}
		b[i]=b[i-1]+a[i-1];
	}
	for(i=1;i<=m;i++){
		printf("%d ",b[i]);
	}
	return 0;
}