class Solution {
/* k只粉笔 i从0开始
每到i需要消耗chalk[i], k -= chalk[i]
如果k < chalk[i],返回i
*/
public int chalkReplacer(int[] chalk, int k) {
int n = chalk.length;
int num = 0;
while(k>=chalk[num]){
k -= chalk[num++];
if(num==n)
num = 0;
}
return num;
}
}