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	`1`	`+## 题目`
	`2`	`+`
	`3`	`+* 118. 杨辉三角`
	`4`	`+`
	`5`	`+给定一个非负整数 numRows,生成「杨辉三角」的前 numRows 行。`
	`6`	`+`
	`7`	`+在「杨辉三角」中,每个数是它左上方和右上方的数的和。`
	`8`	`+`
	`9`	`+## 思路`
	`10`	`+`
	`11`	`+dp[i][j] = dp[i-1][j-1] + dp[i-1][j]`
	`12`	`+`
	`13`	`+`
	`14`	`+## 代码`
	`15`	`+`
	`16`	+```
	`17`	`+class Solution {`
	`18`	`+`
	`19`	`+ /**`
	`20`	`+ * @param Integer $numRows`
	`21`	`+ * @return Integer[][]`
	`22`	`+ */`
	`23`	`+ function generate($numRows) {`
	`24`	`+ /**`
	`25`	`+ 1`
	`26`	`+ 1 1`
	`27`	`+ 1 2 1`
	`28`	`+`
	`29`	`+ dp[i][j] = dp[i-1][j-1] + dp[i-1][j]`
	`30`	`+ */`
	`31`	`+ $dp = [];`
	`32`	`+ for ($i = 0; $i < $numRows; $i++) {`
	`33`	`+ for ($j = 0; $j <= $i; $j++) {`
	`34`	`+ if ($j == 0 \|\| $j == $i) {`
	`35`	`+ $dp[$i][$j] = 1;`
	`36`	`+ } else {`
	`37`	`+ $dp[$i][$j] = $dp[$i-1][$j-1] + $dp[$i-1][$j];`
	`38`	`+ }`
	`39`	`+ }`
	`40`	`+ }`
	`41`	`+ return $dp;`
	`42`	`+ }`
	`43`	`+}`
	`44`	+```

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