LeetCode 寻找数组的中心下标算法题解 All In One

LeetCode 寻找数组的中心下标算法题解 All In One

724. Find Pivot Index

724. 寻找数组的中心下标

"use strict";

/**
 *
 * @author xgqfrms
 * @license MIT
 * @copyright xgqfrms
 * @created 2022-12-28
 * @modified
 *
 * @description 724. Find Pivot Index
 * @description 724. 寻找数组的中心下标
 * @difficulty Easy
 * @ime_complexity O(n)
 * @space_complexity O(n)
 * @augments
 * @example
 * @link https://leetcode.com/problems/find-pivot-index/
 * @link https://leetcode.cn/problems/find-pivot-index/
 * @solutions
 *
 * @best_solutions
 *
 */

export {};

const log = console.log;

function pivotIndex(nums: number[]): number {
  let len = nums.length;
  if(!len) {
    return 0;
  } else {
    let index = 0;
    while(len) {
      const left = nums.slice(0, index).reduce((a,b) => a +=b, 0);
      // ✅ index + 1 
      const right = nums.slice(index + 1).reduce((a,b) => a +=b, 0);
      if(left === right) {
        //break;
        return index;
      }
      index += 1;
      len -= 1;
    }
    return -1;
  }
};


// 测试用例 test cases
const testCases: TestCasesI = [
  {
    input:[1,7,3,6,5,6],
    result: 3,
    desc: 'value equal to 3',
  },
  {
    input: [1,2,3],
    result: -1,
    desc: 'value equal to -1',
  },
  {
    input: [2,1,-1],
    result: 0,
    desc: 'value equal to 0',
  },
];

for (const [i, testCase] of testCases.entries()) {
  const result = pivotIndex(testCase.input);
  log(`test case i result: \n`, result === testCase.result  ? `passed ✅` : `failed ❌`, result);
  // log(`test case i =`, testCase);
}

// npx ts-node ./724\ find-pivot-index.ts

https://leetcode.cn/problems/find-pivot-index/

https://leetcode.com/problems/find-pivot-index/

(🐞 反爬虫测试！打击盗版⚠️）如果你看到这个信息, 说明这是一篇剽窃的文章，请访问 https://www.cnblogs.com/xgqfrms/ 查看原创文章！

refs

https://leetcode.com/study-plan/leetcode-75/?progress=xl5bhjoe

https://leetcode.cn/leetbook/read/top-interview-questions/xmlwi1/

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