初始化兩個座標點，一個每次向右，到達盡頭往下；一個每次向下，到達盡頭往右；列印兩點之間的對角線

public static void zigzag(int[][] arr){
		if(arr==null){
			return;
		}
		
		int ar = 0,ac = 0,br = 0,bc = 0;
		int rl = arr.length-1;
		int cl = arr[0].length-1;
		boolean flag = false;
		
		while(ar!=rl+1){
			zPrint(arr,ar,ac,br,bc,flag);
			
			ar = ac == cl ? ++ar:ar;
			ac = ac == cl ? ac:++ac;
			bc = br == rl ? ++bc:bc;
			br = br == rl ? br:++br;
			
			flag = !flag;
		}
		
		
	}
	
	public static void zPrint(int[][] arr,int ar,int ac,int br,int bc,boolean flag){
		if(flag){
			while(ar != br+1){
				System.out.print(arr[ar++][ac--]+",");
			}
		}else{
			while(br!=ar-1){
				System.out.print(arr[br--][bc++]+",");
			}
		}
		
	}